Seafarers: Cloth for Catan and The Forgotten Tribe

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01TWwLCrXa9aFVg8dZsCdLBZ

CLAUDE.md

@@ -51,14 +51,14 @@ integration:
 
 ## Katan
 
-The island game is catalogue id `catan`, shown as **Katan**. It has two rule
-sets chosen at setup: the base game (`docs/RULES-catan.md`), Cities & Knights
+The island game is catalogue id `catan`, shown as **Katan**. It has two expansions
+(toggles, `CatanOptions.expansions`; none on is the base game): the base game (`docs/RULES-catan.md`), Cities & Knights
 (`docs/RULES-catan-ck.md`, code in `game/catan/CatanCk*.kt`, state behind
 `CatanState.ck`, which is null in the base game) and Seafarers
 (`docs/RULES-catan-seafarers.md`, code in `game/catan/CatanSea*.kt`, state behind
-`CatanState.sea`). The base and Seafarers rules read the board from `state.topo`, not from
+`CatanState.sea`); the two can be switched on together. The base and Seafarers rules read the board from `state.topo`, not from
 `CatanBoard` directly, because a Seafarers map is not the 19-hex island
-(Cities & Knights is always the standard island and still uses `CatanBoard`). The
+(Cities & Knights also reads `state.topo`, so it runs on a Seafarers map too). The
 Catan Universe reverse engineering that shaped the landscape HUD and trade board
 is in `docs/RE-catan-universe.md`. The screen is layered; see
 `docs/UI-catan.md` before changing it.

app/src/main/java/org/prolibertate/games/game/catan/CatanAi.kt

@@ -189,7 +189,7 @@ class CatanAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) : GameAi<Ca
         have.toDouble() / cost.values.sum() + if (covers(hand, cost)) 1.0 else 0.0
     }
 
-    private fun chooseGold(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): CatanMove {
+    internal fun chooseGold(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): CatanMove {
         val picks = legal.filterIsInstance<PickGold>()
         if (picks.isEmpty()) return legal.first()
         return when (profile.level) {
@@ -592,6 +592,20 @@ class CatanAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) : GameAi<Ca
     // -----------------------------------------------------------------------
 
     /** What a seat would think of building on [vertex]: production and ports. */
+    /** What a spot beside a cloth village or an unclaimed tribe chip is worth beyond its cards. */
+    private fun scenarioLure(state: CatanState, vertex: Int): Double {
+        val sea = state.sea ?: return 0.0
+        var lure = 0.0
+        for (h in state.topo.VERTEX_HEXES[vertex]) {
+            // A cloth token is a quarter-point, rolled as often as its number comes up.
+            if (state.terrains[h] == Terrain.VILLAGE && sea.villageCloth.getOrElse(h) { 0 } > 0) {
+                lure += CatanBoard.numberOdds(state.numbers[h]) / 36.0 * CLOTH_WORTH
+            }
+            if (sea.chips.getOrNull(h).let { it != null && it != TribeChip.NONE }) lure += CHIP_LURE
+        }
+        return lure
+    }
+
     internal fun spotValue(state: CatanState, vertex: Int): Double {
         if (state.buildings[vertex] != null) return -1.0
         var value = 0.0
@@ -602,6 +616,7 @@ class CatanAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) : GameAi<Ca
             kinds += resource
         }
         value += 0.12 * kinds.size // variety keeps a build plan alive
+        value += scenarioLure(state, vertex)
         for (e in state.topo.VERTEX_EDGES[vertex]) {
             val port = state.ports.firstOrNull { it.edge == e } ?: continue
             value += if (port.resource == null) 0.1 else 0.2
@@ -644,9 +659,11 @@ class CatanAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) : GameAi<Ca
             val next = mutableListOf<Int>()
             for (v in frontier) {
                 if (!seen.add(v)) continue
+                // Fog is worth a look: a card on arrival, and land to settle that nobody has seen.
+                if (topo.VERTEX_HEXES[v].any { state.terrains[it] == Terrain.FOG }) best = maxOf(best, FOG_LURE * Math.pow(0.85, depth.toDouble()))
                 if (CatanRules.vertexOpenForSettlement(state, v)) {
                     val island = topo.vertexIsland[v]
-                    val fresh = island >= 0 && island != sea.home && sea.islandBonus[island] == NO_PLAYER
+                    val fresh = island >= 0 && !sea.isStart(island) && sea.islandBonus[island] == NO_PLAYER
                     val value = (spotValue(state, v) + if (fresh) 0.5 else 0.0) * Math.pow(0.85, depth.toDouble())
                     best = maxOf(best, value)
                 }
@@ -673,5 +690,10 @@ class CatanAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) : GameAi<Ca
     private companion object {
         /** A seven makes a seat holding more than this discard half. */
         const val DISCARD_LIMIT = 7
+
+        /** What a ship end beside undiscovered land is worth, on the scale of [spotValue]. */
+        const val FOG_LURE = 0.6
+        const val CLOTH_WORTH = 2.5
+        const val CHIP_LURE = 0.5
     }
 }

app/src/main/java/org/prolibertate/games/game/catan/CatanCk.kt

@@ -171,18 +171,22 @@ object CatanCk {
 
     /** Cities of [seat] that can carry a metropolis or fall to the barbarians' rival: all but metropolises. */
     private fun plainCities(state: CatanState, seat: Int): List<Int> =
-        (0 until CatanBoard.VERTEX_COUNT).filter { v ->
+        (0 until state.topo.VERTEX_COUNT).filter { v ->
             state.buildings[v] == CatanBuilding(BuildingType.CITY, seat) && !hasMetropolis(state, v)
         }
 
     private fun ownsCity(state: CatanState, seat: Int): Boolean =
         state.buildings.any { it == CatanBuilding(BuildingType.CITY, seat) }
 
-    /** Empty crossings at the end of one of [seat]'s roads: where a knight can be put. */
+    /** Whether [seat] has a road, or a ship in Seafarers, on [edge]: the network a knight moves along. */
+    private fun holds(state: CatanState, seat: Int, edge: Int): Boolean =
+        state.roads[edge] == seat || state.sea?.ships?.get(edge) == seat
+
+    /** Empty crossings at the end of one of [seat]'s roads or ships on land: where a knight can be put. */
     private fun knightSpots(state: CatanState, seat: Int): List<Int> =
-        (0 until CatanBoard.VERTEX_COUNT).filter { v ->
-            state.buildings[v] == null && knightAt(state, v) == null &&
-                CatanBoard.VERTEX_EDGES[v].any { state.roads[it] == seat }
+        (0 until state.topo.VERTEX_COUNT).filter { v ->
+            state.topo.vertexLand[v] && state.buildings[v] == null && knightAt(state, v) == null &&
+                state.topo.VERTEX_EDGES[v].any { holds(state, seat, it) }
         }
 
     /**
@@ -196,9 +200,9 @@ object CatanCk {
         val queue = ArrayDeque<Int>().apply { add(from) }
         while (queue.isNotEmpty()) {
             val v = queue.removeFirst()
-            for (e in CatanBoard.VERTEX_EDGES[v]) {
-                if (state.roads[e] != seat) continue
-                val w = CatanBoard.otherEnd(e, v)
+            for (e in state.topo.VERTEX_EDGES[v]) {
+                if (!holds(state, seat, e)) continue
+                val w = state.topo.otherEnd(e, v)
                 if (!seen.add(w)) continue
                 val building = state.buildings[w]
                 val knight = knightAt(state, w)
@@ -215,14 +219,14 @@ object CatanCk {
     private fun destinations(state: CatanState, k: Knight): List<Int> =
         walk(state, k.owner, k.vertex).filter { w ->
             val there = knightAt(state, w)
-            if (state.buildings[w] != null) return@filter false
+            if (state.buildings[w] != null || !state.topo.vertexLand[w]) return@filter false
             there == null || (there.owner != k.owner && there.level < k.level)
         }.sorted()
 
     /** Empty crossings a driven-off [knight] of its owner could still reach. */
     private fun refuges(state: CatanState, knight: Knight): List<Int> =
         walk(state, knight.owner, knight.vertex).filter { w ->
-            state.buildings[w] == null && knightAt(state, w) == null
+            state.buildings[w] == null && state.topo.vertexLand[w] && knightAt(state, w) == null
         }.sorted()
 
     private fun promotable(state: CatanState, k: Knight): Boolean {
@@ -251,6 +255,7 @@ object CatanCk {
             points[seat] += ck.defenderVp[seat] + ck.progressVp[seat]
         }
         ck.merchant?.let { points[it.seat] += 1 }
+        if (state.isSea) for (seat in points.indices) points[seat] += SeaRules.bonusPoints(state, seat)
         return points.toList()
     }
 
@@ -266,15 +271,18 @@ object CatanCk {
             addAll(actionMoves(state, seat))
         }
 
-        CatanPhase.ROBBER -> robberMoves(state, seat)
+        // The bishop moves the robber alone; a seven may send the pirate instead.
+        CatanPhase.ROBBER -> robberMoves(state, seat) +
+            (if (state.isSea && !state.ck!!.bishop) SeaRules.pirateMoves(state, seat) else emptyList())
 
         CatanPhase.PLAYING -> playingMoves(state, seat)
 
         CatanPhase.FREE_ROADS ->
-            CatanRules.roadMoves(state, seat) + listOf<CatanMove>(EndFreeRoads)
+            CatanRules.roadMoves(state, seat) +
+                (if (state.isSea) SeaRules.buildShipMoves(state, seat) else emptyList()) +
+                listOf<CatanMove>(EndFreeRoads)
 
-        // Seafarers is never combined with Cities & Knights.
-        CatanPhase.GOLD -> emptyList()
+        CatanPhase.GOLD -> SeaRules.goldMoves(state)
 
         CatanPhase.TRADE_PENDING -> {
             val offer = state.ck!!.goodsOffer
@@ -327,7 +335,7 @@ object CatanCk {
             if (!k.active && affordable(state, seat, ACTIVATE_COST)) moves += ActivateKnight(k.vertex)
             if (canAct(state, k)) {
                 destinations(state, k).forEach { moves += MoveKnight(k.vertex, it) }
-                if (ck.attacked && k.vertex in CatanBoard.HEX_CORNERS[state.robber]) {
+                if (ck.attacked && k.vertex in state.topo.HEX_CORNERS[state.robber]) {
                     moves += ChaseRobber(k.vertex)
                 }
             }
@@ -340,6 +348,10 @@ object CatanCk {
         val moves = mutableListOf<CatanMove>()
 
         if (affordable(state, seat, CatanRules.ROAD_COST)) moves += CatanRules.roadMoves(state, seat)
+        if (state.isSea) {
+            if (affordable(state, seat, SeaRules.SHIP_COST)) moves += SeaRules.buildShipMoves(state, seat)
+            moves += SeaRules.moveShipMoves(state, seat)
+        }
         if (affordable(state, seat, CatanRules.SETTLEMENT_COST)) {
             moves += CatanRules.settlementVertices(state, seat).map { BuildSettlement(it) }
         }
@@ -380,7 +392,7 @@ object CatanCk {
     /** Own cities with no wall, while the seat has a wall left to build. */
     private fun wallSites(state: CatanState, seat: Int): List<Int> {
         if (wallsOf(state, seat) >= MAX_WALLS) return emptyList()
-        return (0 until CatanBoard.VERTEX_COUNT).filter { v ->
+        return (0 until state.topo.VERTEX_COUNT).filter { v ->
             state.buildings[v] == CatanBuilding(BuildingType.CITY, seat) && v !in state.ck!!.walls
         }
     }
@@ -423,20 +435,37 @@ object CatanCk {
     private fun robberMoves(state: CatanState, seat: Int): List<MoveRobber> {
         val bishop = state.ck!!.bishop
         val moves = mutableListOf<MoveRobber>()
-        for (h in 0 until CatanBoard.HEX_COUNT) {
-            if (h == state.robber) continue
+        for (h in 0 until state.topo.HEX_COUNT) {
+            if (h == state.robber || !state.topo.land[h] || state.terrains[h] == Terrain.FOG) continue
             val victims = victimsAt(state, seat, h)
             when {
-                bishop -> moves += MoveRobber(CatanBoard.HEXES[h])
-                victims.isEmpty() -> moves += MoveRobber(CatanBoard.HEXES[h])
-                else -> victims.forEach { moves += MoveRobber(CatanBoard.HEXES[h], it) }
+                bishop -> moves += MoveRobber(state.topo.HEXES[h])
+                victims.isEmpty() -> moves += MoveRobber(state.topo.HEXES[h])
+                else -> victims.forEach { moves += MoveRobber(state.topo.HEXES[h], it) }
             }
         }
         return moves
     }
 
+    /** The pirate, sent by a seven once the barbarians have landed: it robs a seat with a ship beside it. */
+    fun applyPirate(state: CatanState, seat: Int, move: MovePirate): CatanState {
+        val hex = state.topo.hexIndex[move.hex] ?: throw IllegalArgumentException("No hex at ${move.hex}")
+        var s = state.copy(sea = state.sea!!.copy(pirate = hex), rngStep = state.rngStep + 1)
+        var stole = ""
+        val hand = move.victim?.let { goodsList(s, it) }.orEmpty()
+        if (move.victim != null && hand.isNotEmpty()) {
+            val card = hand[Random(state.seed * 1_000_003L + state.rngStep).nextInt(hand.size)]
+            s = give(s, move.victim, seat, listOf(card))
+            stole = " and takes a ${good(card)} from seat ${move.victim}"
+        }
+        return s.copy(
+            phase = if (state.ck!!.back == Back.AWAIT_ROLL) CatanPhase.AWAIT_ROLL else CatanPhase.PLAYING,
+            log = s.log + "Seat $seat sends the pirate to (${move.hex.q},${move.hex.r})$stole.",
+        )
+    }
+
     private fun victimsAt(state: CatanState, seat: Int, hex: Int): List<Int> =
-        CatanBoard.HEX_CORNERS[hex]
+        state.topo.HEX_CORNERS[hex]
             .mapNotNull { state.buildings[it] }
             .map { it.owner }
             .filter { it != seat }
@@ -445,7 +474,7 @@ object CatanCk {
 
     fun applyRobber(state: CatanState, seat: Int, move: MoveRobber): CatanState {
         val ck = state.ck!!
-        val hex = CatanBoard.hexIndex[move.hex]
+        val hex = state.topo.hexIndex[move.hex]
             ?: throw IllegalArgumentException("No hex at ${move.hex}")
         var s = state.copy(robber = hex, rngStep = state.rngStep + 1)
         val rng = Random(state.seed * 1_000_003L + state.rngStep)
@@ -495,7 +524,7 @@ object CatanCk {
             ProgressType.ENGINEER -> wallSites(state, seat).map { PlayProgress(id, vertex = it) }
 
             ProgressType.INVENTOR -> {
-                val hexes = (0 until CatanBoard.HEX_COUNT).filter { state.numbers[it] in INVENTOR_NUMBERS }
+                val hexes = (0 until state.topo.HEX_COUNT).filter { state.numbers[it] in INVENTOR_NUMBERS }
                 hexes.flatMap { a ->
                     hexes.filter { b -> b > a && state.numbers[b] != state.numbers[a] }
                         .map { b -> PlayProgress(id, hexA = a, hexB = b) }
@@ -530,7 +559,7 @@ object CatanCk {
 
             ProgressType.INTRIGUE ->
                 ck.knights.filter { k ->
-                    k.owner != seat && CatanBoard.VERTEX_EDGES[k.vertex].any { state.roads[it] == seat }
+                    k.owner != seat && state.topo.VERTEX_EDGES[k.vertex].any { holds(state, seat, it) }
                 }.map { PlayProgress(id, vertex = it.vertex) }
 
             ProgressType.SABOTEUR -> listOf(PlayProgress(id))
@@ -559,9 +588,9 @@ object CatanCk {
                 }
 
             ProgressType.MERCHANT ->
-                (0 until CatanBoard.HEX_COUNT).filter { h ->
-                    state.terrains[h] != Terrain.DESERT &&
-                        CatanBoard.HEX_CORNERS[h].any { state.buildings[it]?.owner == seat }
+                (0 until state.topo.HEX_COUNT).filter { h ->
+                    state.terrains[h] != Terrain.DESERT && state.topo.land[h] && state.terrains[h] != Terrain.FOG &&
+                        state.topo.HEX_CORNERS[h].any { state.buildings[it]?.owner == seat }
                 }.map { PlayProgress(id, hexA = it) }
 
             ProgressType.MERCHANT_FLEET -> Good.entries.map { PlayProgress(id, good = it) }
@@ -596,19 +625,19 @@ object CatanCk {
     }
 
     private fun hexesNextTo(state: CatanState, seat: Int, terrain: Terrain): List<Int> =
-        (0 until CatanBoard.HEX_COUNT).filter { h ->
+        (0 until state.topo.HEX_COUNT).filter { h ->
             state.terrains[h] == terrain &&
-                CatanBoard.HEX_CORNERS[h].any { state.buildings[it]?.owner == seat }
+                state.topo.HEX_CORNERS[h].any { state.buildings[it]?.owner == seat }
         }
 
     /** Roads with a loose end: one end touching nothing else of anyone's. */
     private fun openRoads(state: CatanState): List<Int> =
-        (0 until CatanBoard.EDGE_COUNT).filter { e ->
+        (0 until state.topo.EDGE_COUNT).filter { e ->
             if (state.roads[e] == NO_PLAYER) return@filter false
-            val (a, b) = CatanBoard.EDGE_VERTICES[e]
+            val (a, b) = state.topo.EDGE_VERTICES[e]
             listOf(a, b).any { v ->
                 state.buildings[v] == null && knightAt(state, v) == null &&
-                    CatanBoard.VERTEX_EDGES[v].none { it != e && state.roads[it] != NO_PLAYER }
+                    state.topo.VERTEX_EDGES[v].none { it != e && state.roads[it] != NO_PLAYER }
             }
         }
 
@@ -1500,12 +1529,12 @@ object CatanCk {
 
     private fun production(state: CatanState, number: Int): CatanState {
         val gains = List(state.playerCount) { mutableMapOf<Good, Int>() }
-        for (h in 0 until CatanBoard.HEX_COUNT) {
+        for (h in 0 until state.topo.HEX_COUNT) {
             if (state.numbers[h] != number || h == state.robber) continue
             val terrain = state.terrains[h]
             val resource = terrain.produces ?: continue
             val commodity = commodityOf(terrain)
-            for (v in CatanBoard.HEX_CORNERS[h]) {
+            for (v in state.topo.HEX_CORNERS[h]) {
                 val building = state.buildings[v] ?: continue
                 val mine = gains[building.owner]
                 fun add(good: Good, n: Int) { mine[good] = (mine[good] ?: 0) + n }
@@ -1539,6 +1568,7 @@ object CatanCk {
         }
         val said = if (notes.isEmpty()) "nothing for anyone" else notes.joinToString(", ")
         s = s.copy(log = s.log + "The dice pay: $said.")
+        if (state.isSea) s = SeaRules.payCloth(s, number)
 
         // The aqueduct: a seat that was paid nothing may take a resource of its choice.
         val order = (0 until s.playerCount).map { (s.turn + it) % s.playerCount }
@@ -1546,7 +1576,11 @@ object CatanCk {
             improvement(s, seat, Track.SCIENCE) >= IMPROVEMENT_POWER_LEVEL && gains[seat].values.sum() == 0
         }
         val queued = enqueue(s, dry.map { AqueductChore(it) }, Back.AFTER_PRODUCTION)
-        return if (queued.ck!!.chores.isNotEmpty()) queued else queued.copy(phase = CatanPhase.PLAYING)
+        val next = if (queued.ck!!.chores.isNotEmpty()) queued else queued.copy(phase = CatanPhase.PLAYING)
+        // Gold is chosen before anything else; the chores (and then play) wait behind it.
+        val gold = if (state.isSea) CatanRules.goldOwed(state, number) else emptyList()
+        if (gold.isEmpty()) return next
+        return SeaRules.settleGold(next.copy(sea = next.sea!!.copy(gold = gold, afterGold = next.phase)))
     }
 
     // -----------------------------------------------------------------------

app/src/main/java/org/prolibertate/games/game/catan/CatanCkAi.kt

@@ -53,7 +53,9 @@ internal class CatanCkAi(
 
         CatanPhase.PLAYING -> choosePlaying(state, seat, legal, profile)
 
-        CatanPhase.DISCARDING, CatanPhase.GOLD, CatanPhase.GAME_OVER -> legal.firstOrNull()
+        CatanPhase.GOLD -> ai.chooseGold(state, seat, legal, profile)
+
+        CatanPhase.DISCARDING, CatanPhase.GAME_OVER -> legal.firstOrNull()
             ?: error("Nothing to choose in phase ${state.phase}")
     }
 
@@ -131,9 +133,9 @@ internal class CatanCkAi(
         val leader = (0 until state.playerCount).filter { it != seat }.maxByOrNull { points[it] }
         val victimWeight = 0.3 + 0.1 * profile.style.boldness
         fun score(move: MoveRobber): Double {
-            val hex = CatanBoard.hexIndex.getValue(move.hex)
+            val hex = state.topo.hexIndex.getValue(move.hex)
             var score = 0.0
-            for (v in CatanBoard.HEX_CORNERS[hex]) {
+            for (v in state.topo.HEX_CORNERS[hex]) {
                 val building = state.buildings[v] ?: continue
                 val worth = if (building.type == BuildingType.CITY) 2 else 1
                 val odds = CatanBoard.numberOdds(state.numbers[hex]) / 36.0
@@ -178,7 +180,7 @@ internal class CatanCkAi(
         // Chase the robber off a hex it is squatting on.
         if (ck.attacked) {
             val onMine = legal.filterIsInstance<ChaseRobber>().firstOrNull()
-            val robberHurtsMe = CatanBoard.HEX_CORNERS[state.robber].any { state.buildings[it]?.owner == seat }
+            val robberHurtsMe = state.topo.HEX_CORNERS[state.robber].any { state.buildings[it]?.owner == seat }
             if (onMine != null && robberHurtsMe) return onMine
         }
 
@@ -212,6 +214,12 @@ internal class CatanCkAi(
             settlements.maxByOrNull { ai.spotValue(state, it.vertex) }?.let { return it }
         }
 
+        // Seafarers: a ship toward land nobody has settled is worth more than a card.
+        legal.filterIsInstance<BuildShip>()
+            .filter { ai.shipValue(state, seat, it.edge) > 0.5 }
+            .maxByOrNull { ai.shipValue(state, seat, it.edge) }
+            ?.let { return it }
+
         // Improvements spend cards nothing else needs. Favour the track furthest along.
         legal.filterIsInstance<BuyImprovement>()
             .maxByOrNull { CatanCk.improvement(state, seat, it.track) * 10 + trackLean(it.track) }
@@ -226,6 +234,11 @@ internal class CatanCkAi(
             if (CatanCk.goodsCount(state, seat) >= (if (boldness < 0) 5 else 7)) return it
         }
 
+        legal.filterIsInstance<BuildShip>()
+            .filter { ai.shipValue(state, seat, it.edge) > 0.15 }
+            .maxByOrNull { ai.shipValue(state, seat, it.edge) }
+            ?.let { return it }
+
         legal.filterIsInstance<BuildRoad>()
             .filter { ai.roadValue(state, it) > 0.1 - 0.04 * boldness }
             .maxByOrNull { ai.roadValue(state, it) }
@@ -360,7 +373,7 @@ internal class CatanCkAi(
 
     /** What a building on [vertex] would draw, by the odds of its hexes and what the seat wants. */
     private fun production(state: CatanState, vertex: Int): Double =
-        CatanBoard.VERTEX_HEXES[vertex].sumOf { h ->
+        state.topo.VERTEX_HEXES[vertex].sumOf { h ->
             val want = state.terrains[h].produces?.let { ai.want(it) } ?: 0.0
             want * CatanBoard.numberOdds(state.numbers[h]) / 36.0
         }

app/src/main/java/org/prolibertate/games/game/catan/CatanModel.kt

@@ -1,7 +1,16 @@
 package org.prolibertate.games.game.catan
 
+import kotlinx.serialization.KSerializer
 import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
+import kotlinx.serialization.descriptors.SerialDescriptor
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
+import kotlinx.serialization.json.JsonArray
+import kotlinx.serialization.json.JsonDecoder
+import kotlinx.serialization.json.JsonObject
+import kotlinx.serialization.json.JsonPrimitive
+import kotlinx.serialization.json.jsonObject
 
 /** Sentinel stored in [CatanState.roads] for an unclaimed road position. */
 const val NO_PLAYER = -1
@@ -45,6 +54,15 @@ enum class Terrain(val produces: Resource?) {
 
     /** Seafarers: a gold field. A settlement beside it takes any resource its owner likes when its number rolls. */
     GOLD(null),
+
+    /**
+     * Seafarers: land not yet found. It becomes a resource or gold when a road or ship first reaches it
+     * (`SeaState.fogDeck`). Until then nothing is built on it, nothing produces, and the robber keeps off.
+     */
+    FOG(null),
+
+    /** Seafarers, Cloth for Catan: a village. It pays cloth, not cards, to the settlements around it when its number rolls. */
+    VILLAGE(null),
 }
 
 /** Axial coordinate of one hex on the board. See [CatanBoard]. */
@@ -151,12 +169,9 @@ enum class CatanPhase {
     CHORE,
 }
 
-/** Which rules a table plays. The expansion is a whole rule set, not a toggle. */
+/** An expansion a table can switch on. The base game is what is left with none selected. */
 @Serializable
-enum class CatanRuleSet {
-    /** The base game: development cards, Largest Army, a robber from the start. */
-    BASE,
-
+enum class CatanExpansion {
     /** Cities & Knights: commodities, knights, barbarians, city improvements. */
     CITIES_AND_KNIGHTS,
 
@@ -164,16 +179,57 @@ enum class CatanRuleSet {
     SEAFARERS,
 }
 
-@Serializable
+/**
+ * What a table plays: the expansions switched on, and the Seafarers map when that one is.
+ *
+ * Saves written before expansions became toggles carry `"ruleSet"` instead of `"expansions"`;
+ * [CatanOptionsSerializer] reads either.
+ */
+@Serializable(with = CatanOptionsSerializer::class)
 data class CatanOptions(
     val playerCount: Int = 3,
     val pointsToWin: Int = 10,
-    val ruleSet: CatanRuleSet = CatanRuleSet.BASE,
+    val expansions: Set<CatanExpansion> = emptySet(),
+    val scenario: SeaScenario = SeaScenario.NEW_SHORES,
 ) {
     init {
         require(playerCount in 3..4) { "The island seats three or four players" }
         require(pointsToWin >= 2) { "pointsToWin must be at least 2" }
     }
+
+    val seafarers: Boolean get() = CatanExpansion.SEAFARERS in expansions
+    val citiesAndKnights: Boolean get() = CatanExpansion.CITIES_AND_KNIGHTS in expansions
+}
+
+/** The wire shape of [CatanOptions]. */
+@Serializable
+private class CatanOptionsWire(
+    val playerCount: Int = 3,
+    val pointsToWin: Int = 10,
+    val expansions: Set<CatanExpansion> = emptySet(),
+    val scenario: SeaScenario = SeaScenario.NEW_SHORES,
+)
+
+/** Reads the legacy single `ruleSet` field as an expansion set. */
+object CatanOptionsSerializer : KSerializer<CatanOptions> {
+    override val descriptor: SerialDescriptor = CatanOptionsWire.serializer().descriptor
+
+    override fun serialize(encoder: Encoder, value: CatanOptions) = encoder.encodeSerializableValue(
+        CatanOptionsWire.serializer(),
+        CatanOptionsWire(value.playerCount, value.pointsToWin, value.expansions, value.scenario),
+    )
+
+    override fun deserialize(decoder: Decoder): CatanOptions {
+        val input = decoder as JsonDecoder
+        var obj = input.decodeJsonElement().jsonObject
+        val legacy = (obj["ruleSet"] as? JsonPrimitive)?.content
+        if (legacy != null) {
+            val expansions = if (legacy == "BASE") emptyList() else listOf(JsonPrimitive(legacy))
+            obj = JsonObject(obj - "ruleSet" + ("expansions" to JsonArray(expansions)))
+        }
+        val wire = input.json.decodeFromJsonElement(CatanOptionsWire.serializer(), obj)
+        return CatanOptions(wire.playerCount, wire.pointsToWin, wire.expansions, wire.scenario)
+    }
 }
 
 /**
@@ -198,6 +254,8 @@ data class CatanState(
     val turn: Int,
     /** How many setup placements are done, 0 until 2 * playerCount. */
     val setupIndex: Int,
+    /** The seat that places first and takes the first turn; drawn from the table seed. */
+    val firstSeat: Int = 0,
     /** Monotonic turn counter, 0 during setup, 1 from the first real turn. */
     val turnNumber: Int,
     /** Terrain per hex, indexed like [CatanBoard.HEXES]. */
@@ -414,12 +472,53 @@ data class SeaState(
     val shipMoved: Boolean = false,
     /** Who holds the "new island" bonus for each island, or [NO_PLAYER]. The home island's is never awarded. */
     val islandBonus: List<Int>,
-    /** The island the players start on. */
+    /** The island that counts as home: the largest, and the pirate-free start of the original map. */
     val home: Int,
+    /** The islands the starting settlements may go on. Empty in a save from before there were several: just [home]. */
+    val starts: List<Int> = emptyList(),
     /** Gold owed after a roll, front first: each seat chooses [GoldOwed.count] cards. */
     val gold: List<GoldOwed> = emptyList(),
+    /**
+     * The tiles still face down, next to be found first. Hidden from every view but the host's, like the
+     * development deck.
+     */
+    val fogDeck: List<FogTile> = emptyList(),
+    /** Where the game goes when the gold queue empties: [CatanPhase.PLAYING] unless a find interrupted something else. */
+    val afterGold: CatanPhase? = null,
+    /** Cloth tokens each seat holds (Cloth for Catan); empty when the scenario has none. Two make a victory point. */
+    val cloth: List<Int> = emptyList(),
+    /** Cloth still on each hex's village, by hex (Cloth for Catan); empty when the scenario has none. */
+    val villageCloth: List<Int> = emptyList(),
+    /** The tribe chip waiting on each hex (Forgotten Tribe), by hex; empty when the scenario has none. */
+    val chips: List<TribeChip> = emptyList(),
+    /** Seats that took a harbour chip and so trade 3:1 anywhere. */
+    val harbourSeats: List<Int> = emptyList(),
+    /** Victory points each seat holds from tribe chips; empty until one is taken. */
+    val chipPoints: List<Int> = emptyList(),
 )
 
+/** What the first settler beside a tribe hex takes (Forgotten Tribe). */
+@Serializable
+enum class TribeChip {
+    NONE,
+
+    /** One victory point. */
+    POINT,
+
+    /** A 3:1 harbour, good wherever the seat trades. */
+    HARBOUR,
+
+    /** Two resources of the seat's choice. */
+    GOLD,
+}
+
+/** One tile of the fog: what the hex turns out to be and the number token that comes with it. */
+@Serializable
+data class FogTile(val terrain: Terrain, val number: Int)
+
+/** Whether [island] is one the game starts on, and so never earns the new-island bonus. */
+fun SeaState.isStart(island: Int): Boolean = island == home || island in starts
+
 @Serializable
 data class GoldOwed(val seat: Int, val count: Int)
 

app/src/main/java/org/prolibertate/games/game/catan/CatanRules.kt

@@ -54,15 +54,15 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             "Seat count ${config.seats.size} does not match ${options.playerCount} players"
         }
 
-        val sea = options.ruleSet == CatanRuleSet.SEAFARERS
-        val scenario = SeaScenario.NEW_SHORES
+        val sea = options.seafarers
+        val scenario = options.scenario
         val seaBoard = if (sea) SeaBoards.generate(scenario, config.seed) else null
         val topo = if (seaBoard != null) SeaBoards.topology(scenario) else CatanBoard.base
         val board = seaBoard?.let { CatanBoard.Generated(it.terrains, it.numbers, it.robber, it.ports) }
             ?: CatanBoard.generate(config.seed)
         // A different random stream than the island, so the same seed still
         // produces both a fixed island and a fixed deck.
-        val ck = options.ruleSet == CatanRuleSet.CITIES_AND_KNIGHTS
+        val ck = options.citiesAndKnights
         // Cities & Knights has no development cards: knights and progress
         // cards take their place.
         val devDeck = if (ck) {
@@ -73,12 +73,17 @@ object CatanRules : GameRules<CatanState, CatanMove> {
                 .shuffled(Random(config.seed + 1))
         }
 
+        // Seat 0 used to lead every game; a separate stream from the board and
+        // the deck keeps the same seed giving the same table.
+        val firstSeat = Random(config.seed + 2).nextInt(options.playerCount)
+
         return CatanState(
             options = options,
             seed = config.seed,
             phase = CatanPhase.SETUP_FIRST,
-            turn = 0,
+            turn = firstSeat,
             setupIndex = 0,
+            firstSeat = firstSeat,
             turnNumber = 0,
             terrains = board.terrains,
             numbers = board.numbers,
@@ -114,6 +119,11 @@ object CatanRules : GameRules<CatanState, CatanMove> {
                     pirate = it.pirate,
                     islandBonus = List(topo.islandCount) { NO_PLAYER },
                     home = it.home,
+                    starts = it.starts,
+                    fogDeck = it.fogDeck,
+                    cloth = if (it.villageCloth.isEmpty()) emptyList() else List(options.playerCount) { 0 },
+                    villageCloth = it.villageCloth,
+                    chips = it.chips,
                 )
             },
         )
@@ -121,8 +131,9 @@ object CatanRules : GameRules<CatanState, CatanMove> {
 
     override fun currentSeat(state: CatanState): Int? = when (state.phase) {
         CatanPhase.GAME_OVER -> null
-        CatanPhase.SETUP_FIRST -> state.setupIndex
-        CatanPhase.SETUP_SECOND -> 2 * state.playerCount - 1 - state.setupIndex
+        CatanPhase.SETUP_FIRST -> (state.firstSeat + state.setupIndex) % state.playerCount
+        CatanPhase.SETUP_SECOND ->
+            (state.firstSeat + 2 * state.playerCount - 1 - state.setupIndex) % state.playerCount
         CatanPhase.DISCARDING -> state.discardSeat
         CatanPhase.TRADE_PENDING -> state.pendingTrade?.asking?.takeIf { it >= 0 }
             ?: state.ck?.goodsOffer?.asking?.takeIf { it >= 0 }
@@ -201,8 +212,10 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         val moves = mutableListOf<SetupPlace>()
         for (v in 0 until state.topo.VERTEX_COUNT) {
             if (!vertexOpenForSettlement(state, v)) continue
-            // Seafarers: everyone starts on the home island.
-            if (state.sea != null && state.topo.vertexIsland[v] != state.sea.home) continue
+            // Seafarers: the starting settlements go on a starting island.
+            if (state.sea != null && !state.sea.isStart(state.topo.vertexIsland[v])) continue
+            // Nobody starts beside land that has not been found.
+            if (state.topo.VERTEX_HEXES[v].any { state.terrains[it] == Terrain.FOG }) continue
             for (e in state.topo.VERTEX_EDGES[v]) {
                 if (state.roads[e] != NO_PLAYER || !state.topo.edgeLand[e]) continue
                 moves += SetupPlace(v, e)
@@ -238,7 +251,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
     private fun robberMoves(state: CatanState, seat: Int): List<MoveRobber> {
         val moves = mutableListOf<MoveRobber>()
         for (h in 0 until state.topo.HEX_COUNT) {
-            if (h == state.robber || !state.topo.land[h]) continue
+            if (h == state.robber || !state.topo.land[h] || state.terrains[h] == Terrain.FOG) continue
             val victims = state.topo.HEX_CORNERS[h]
                 .mapNotNull { state.buildings[it] }
                 .map { it.owner }
@@ -512,9 +525,9 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         return when {
             newIndex >= 2 * n -> s.copy(
                 phase = CatanPhase.AWAIT_ROLL,
-                turn = 0,
+                turn = state.firstSeat,
                 turnNumber = 1,
-                log = s.log + "Setup done — seat 0 leads.",
+                log = s.log + "Setup done — seat ${state.firstSeat} leads.",
             )
 
             newIndex == n -> s.copy(phase = CatanPhase.SETUP_SECOND)
@@ -586,12 +599,13 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         s = s.copy(
             log = s.log + "Seat ${state.turn} rolls ${state.lastDice.joinToString(" + ")} — $said.",
         )
+        if (state.isSea) s = SeaRules.payCloth(s, number)
         if (goldOwed.isEmpty()) return s
         return SeaRules.settleGold(s.copy(sea = s.sea!!.copy(gold = goldOwed)))
     }
 
     /** What each seat is owed for gold fields showing [number], in seat order from the roller. */
-    private fun goldOwed(state: CatanState, number: Int): List<GoldOwed> {
+    internal fun goldOwed(state: CatanState, number: Int): List<GoldOwed> {
         val topo = state.topo
         val owed = IntArray(state.playerCount)
         for (h in 0 until topo.HEX_COUNT) {
@@ -654,7 +668,9 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             s = s.copy(pendingFreeRoads = left)
             if (left == 0) s = s.copy(phase = phaseAfterRoads(s))
         }
-        return checkWin(s.copy(log = s.log + "Seat $seat builds a road on ${move.edge}."))
+        s = s.copy(log = s.log + "Seat $seat builds a road on ${move.edge}.")
+        if (state.sea != null) s = SeaRules.reveal(s, seat, move.edge)
+        return checkWin(s)
     }
 
     private fun applyBuildShip(state: CatanState, seat: Int, move: BuildShip): CatanState {
@@ -673,7 +689,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             s = s.copy(pendingFreeRoads = left)
             if (left == 0) s = s.copy(phase = phaseAfterRoads(s))
         }
-        return checkWin(s.copy(log = s.log + "Seat $seat launches a ship on ${move.edge}."))
+        return checkWin(SeaRules.reveal(s.copy(log = s.log + "Seat $seat launches a ship on ${move.edge}."), seat, move.edge))
     }
 
     private fun applyMoveShip(state: CatanState, seat: Int, move: MoveShip): CatanState {
@@ -686,12 +702,17 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         val s = state.copy(
             sea = sea.copy(ships = ships, shipMoved = true, builtThisTurn = sea.builtThisTurn + move.to),
         )
-        return checkWin(refreshLongestRoad(s).let {
-            it.copy(log = it.log + "Seat $seat sails a ship from ${move.from} to ${move.to}.")
-        })
+        return checkWin(
+            SeaRules.reveal(
+                refreshLongestRoad(s).let { it.copy(log = it.log + "Seat $seat sails a ship from ${move.from} to ${move.to}.") },
+                seat,
+                move.to,
+            ),
+        )
     }
 
     private fun applyMovePirate(state: CatanState, seat: Int, move: MovePirate): CatanState {
+        if (state.isCk) return CatanCk.applyPirate(state, seat, move)
         val hex = state.topo.hexIndex[move.hex] ?: throw IllegalArgumentException("No hex at ${move.hex}")
         var s = state.copy(sea = state.sea!!.copy(pirate = hex), rngStep = state.rngStep + 1)
         var stolen = ""
@@ -726,7 +747,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             },
         )
         s = payCost(s, seat, SETTLEMENT_COST)
-        s = SeaRules.claimIsland(s, seat, move.vertex)
+        s = SeaRules.settled(s, seat, move.vertex)
         // A settlement can break another player's road, so the award is
         // recomputed for everyone.
         s = refreshLongestRoad(s)
@@ -1129,7 +1150,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         cards.groupingBy { it }.eachCount()
 
     /** Hands with [delta] of each resource added to (or, with negative sign, removed from) [seat]'s. */
-    private fun withCounts(
+    internal fun withCounts(
         resources: List<Map<Resource, Int>>,
         seat: Int,
         delta: Map<Resource, Int>,
@@ -1167,6 +1188,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             val mine = state.buildings[a]?.owner == seat || state.buildings[b]?.owner == seat
             if (mine) best = port.ratio
         }
+        if (best > 3 && state.sea?.harbourSeats?.contains(seat) == true) best = 3
         return best
     }
 
@@ -1177,7 +1199,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             val (a, b) = state.topo.EDGE_VERTICES[port.edge]
             if (state.buildings[a]?.owner == seat || state.buildings[b]?.owner == seat) return port.ratio
         }
-        return 4
+        return if (state.sea?.harbourSeats?.contains(seat) == true) 3 else 4
     }
 
     // -----------------------------------------------------------------------
@@ -1198,6 +1220,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         state.copy(
             // Hidden information stays with the holder and the host.
             devDeck = emptyList(),
+            sea = state.sea?.copy(fogDeck = emptyList()),
             devHands = state.devHands.mapIndexed { index, hand ->
                 if (index == seat) hand else emptyList()
             },

app/src/main/java/org/prolibertate/games/game/catan/CatanSeaBoard.kt

@@ -5,11 +5,44 @@ import kotlin.random.Random
 
 /** The Seafarers maps on offer. Each is a fixed arrangement of land and sea; the tiles and numbers on it are shuffled. */
 @Serializable
-enum class SeaScenario(val title: String, val blurb: String) {
+enum class SeaScenario(val title: String, val blurb: String, val start: SeaStart = SeaStart.HOME_ONLY) {
     NEW_SHORES(
         "Heading for New Shores",
         "One large home island and three small ones to find by ship. Gold fields on two of the small islands.",
     ),
+    FOUR_ISLANDS(
+        "Four Islands",
+        "Four equal islands, one start each, and two gold islets in the middle. Settle your own island, then sail.",
+        SeaStart.MAIN_ISLANDS,
+    ),
+    THROUGH_THE_DESERT(
+        "Through the Desert",
+        "One island cut by a broad desert that yields nothing. Reach the far side by road, or sail round to the islets.",
+    ),
+    FOG_ISLANDS(
+        "The Fog Islands",
+        "A home island, an islet, and a bank of fog. Land in the fog is face down until a road or ship reaches it; " +
+            "the finder takes a card of what lies there.",
+    ),
+    CLOTH_FOR_CATAN(
+        "Cloth for Catan",
+        "Four villages weave cloth. Settle beside one and it pays you a cloth token whenever its number rolls; " +
+            "every two tokens are a victory point.",
+    ),
+    FORGOTTEN_TRIBE(
+        "The Forgotten Tribe",
+        "Four small isles hold the chips of a lost tribe. The first to settle beside one takes it: " +
+            "a victory point, a harbour, or gold.",
+    ),
+}
+
+/** Where the starting settlements may go. */
+enum class SeaStart {
+    /** The largest island only. */
+    HOME_ONLY,
+
+    /** Any island big enough to live on (four hexes or more); the small ones are prizes to sail to. */
+    MAIN_ISLANDS,
 }
 
 /**
@@ -33,8 +66,73 @@ object SeaBoards {
         "..........",
     )
 
+    private val FOUR_ISLANDS_MAP = listOf(
+        "............",
+        "..###..###..",
+        "..###..###..",
+        "............",
+        "..$.....$...",
+        "............",
+        "..###..###..",
+        "..###..###..",
+        "............",
+    )
+
+    private val THROUGH_THE_DESERT_MAP = listOf(
+        "............",
+        ".###DD###...",
+        ".###DDD###..",
+        "..###DD###..",
+        "............",
+        "..$.....$...",
+        "............",
+        "...##...#...",
+        "............",
+    )
+
+    /** `F` is fog: land that is face down until found. */
+    private val FOG_ISLANDS_MAP = listOf(
+        "............",
+        ".###....FF..",
+        ".####..FFF..",
+        "..#D#..FFFF.",
+        ".###...FFF..",
+        ".......FF...",
+        "...##.......",
+        "............",
+    )
+
+    /** `V` is a village; `t` is a resource hex that carries a tribe chip. */
+    private val CLOTH_FOR_CATAN_MAP = listOf(
+        "............",
+        "..V###..V##.",
+        "..#####..##.",
+        "..####V..#..",
+        "...###......",
+        ".......##V..",
+        "............",
+        "...##.......",
+        "............",
+    )
+
+    private val FORGOTTEN_TRIBE_MAP = listOf(
+        "............",
+        "..###..t#...",
+        "..#####..#t.",
+        "..#####..#..",
+        "..####......",
+        "........t##.",
+        ".#t.........",
+        "............",
+    )
+
     private fun rows(scenario: SeaScenario): List<String> = when (scenario) {
         SeaScenario.NEW_SHORES -> NEW_SHORES_MAP
+        SeaScenario.FOUR_ISLANDS -> FOUR_ISLANDS_MAP
+        SeaScenario.THROUGH_THE_DESERT -> THROUGH_THE_DESERT_MAP
+        SeaScenario.FOG_ISLANDS -> FOG_ISLANDS_MAP
+        SeaScenario.CLOTH_FOR_CATAN -> CLOTH_FOR_CATAN_MAP
+        SeaScenario.FORGOTTEN_TRIBE -> FORGOTTEN_TRIBE_MAP
     }
 
     private val topologies = HashMap<SeaScenario, Topology>()
@@ -72,8 +170,22 @@ object SeaBoards {
         val pirate: Int,
         val ports: List<Port>,
         val home: Int,
+        /** The islands the starting settlements may go on; always includes [home]. */
+        val starts: List<Int> = listOf(home),
+        /** The tiles under the fog, in the order they will be found. */
+        val fogDeck: List<FogTile> = emptyList(),
+        /** The tribe chip on each hex, or [TribeChip.NONE]; empty when the map has none. */
+        val chips: List<TribeChip> = emptyList(),
+        /** Cloth waiting on each village, by hex; empty when the map has none. */
+        val villageCloth: List<Int> = emptyList(),
     )
 
+    /** An island of this many land hexes or more can be started on. */
+    private const val MAIN_ISLAND_HEXES = 4
+
+    /** Cloth each village starts with. */
+    const val VILLAGE_CLOTH = 6
+
     private val RESOURCE_TILES = listOf(
         Terrain.FOREST, Terrain.PASTURE, Terrain.FIELDS, Terrain.HILLS, Terrain.MOUNTAINS,
     )
@@ -88,18 +200,21 @@ object SeaBoards {
         val random = Random(seed)
 
         // Resources fill the '#' hexes as evenly as the count allows, in shuffled order.
-        val plain = kinds.indices.filter { kinds[it] == '#' }
+        val plain = kinds.indices.filter { kinds[it] == '#' || kinds[it] == 't' }
         val pool = List(plain.size) { RESOURCE_TILES[it % RESOURCE_TILES.size] }.shuffled(random)
         val terrains = MutableList(kinds.size) { Terrain.SEA }
         kinds.forEachIndexed { h, ch ->
             terrains[h] = when (ch) {
                 '$' -> Terrain.GOLD
                 'D' -> Terrain.DESERT
-                '#' -> pool[plain.indexOf(h)]
+                '#', 't' -> pool[plain.indexOf(h)]
+                'V' -> Terrain.VILLAGE
+                'F' -> Terrain.FOG
                 else -> Terrain.SEA
             }
         }
 
+        // The fog hexes take part as slots, so the tokens they hide are dealt from the same pile.
         val numbered = terrains.indices.filter { terrains[it] != Terrain.SEA && terrains[it] != Terrain.DESERT }
         check(numbered.size <= TOKENS.size) { "Not enough number tokens for ${numbered.size} hexes" }
         val tokens = TOKENS.take(numbered.size).shuffled(random)
@@ -119,6 +234,14 @@ object SeaBoards {
             attempt++
         }
 
+        // What lies under the fog: mostly resources, one gold field in five, drawn from the same tokens.
+        val fogHexes = terrains.indices.filter { terrains[it] == Terrain.FOG }
+        val fogKinds = List(fogHexes.size) { i ->
+            if (i % 5 == 4) Terrain.GOLD else RESOURCE_TILES[i % RESOURCE_TILES.size]
+        }.shuffled(random)
+        val fogDeck = fogHexes.mapIndexed { i, h -> FogTile(fogKinds[i], numbers[h]) }.shuffled(random)
+        fogHexes.forEach { numbers[it] = 0 }
+
         val portTypes = (
             listOf(Resource.LUMBER, Resource.BRICK, Resource.WOOL, Resource.GRAIN, Resource.ORE) + List(4) { null }
             ).shuffled(random)
@@ -129,7 +252,10 @@ object SeaBoards {
 
         val desert = terrains.indexOf(Terrain.DESERT).takeIf { it >= 0 }
             ?: numbered.first()
-        val home = (0 until topo.islandCount).maxByOrNull { island -> topo.islandOf.count { it == island } } ?: 0
+        // Home is the largest island that is not under the fog: nobody starts on land they cannot see.
+        val fogged = fogHexes.map { topo.islandOf[it] }.toSet()
+        val home = (0 until topo.islandCount).filter { it !in fogged }
+            .maxByOrNull { island -> topo.islandOf.count { it == island } } ?: 0
         // The pirate starts in the open sea: the sea hex farthest from every shore.
         val sea = terrains.indices.filter { terrains[it] == Terrain.SEA }
         val pirate = sea.maxByOrNull { h ->
@@ -139,6 +265,28 @@ object SeaBoards {
             } ?: 0
         } ?: sea.first()
 
-        return Generated(terrains, numbers.toList(), desert, pirate, ports, home)
+        val starts = when (scenario.start) {
+            SeaStart.HOME_ONLY -> listOf(home)
+            SeaStart.MAIN_ISLANDS -> (0 until topo.islandCount).filter { island ->
+                topo.islandOf.count { it == island } >= MAIN_ISLAND_HEXES
+            }.ifEmpty { listOf(home) }
+        }
+
+        // Tribe chips: one of each kind in turn, dealt to the marked hexes in random order.
+        val chipHexes = kinds.indices.filter { kinds[it] == 't' }
+        val chips = if (chipHexes.isEmpty()) {
+            emptyList()
+        } else {
+            val kindsOfChip = listOf(TribeChip.POINT, TribeChip.HARBOUR, TribeChip.GOLD)
+            val dealt = List(chipHexes.size) { kindsOfChip[it % kindsOfChip.size] }.shuffled(random)
+            List(terrains.size) { h -> chipHexes.indexOf(h).let { if (it < 0) TribeChip.NONE else dealt[it] } }
+        }
+        val villages = if (kinds.none { it == 'V' }) {
+            emptyList()
+        } else {
+            List(terrains.size) { h -> if (terrains[h] == Terrain.VILLAGE) VILLAGE_CLOTH else 0 }
+        }
+
+        return Generated(terrains, numbers.toList(), desert, pirate, ports, home, starts, fogDeck, chips, villages)
     }
 }

app/src/main/java/org/prolibertate/games/game/catan/CatanSeaRules.kt

@@ -83,7 +83,7 @@ internal object SeaRules {
             .map { sea.ships[it] }
             .filter { it != NO_PLAYER && it != thief }
             .distinct()
-            .filter { state.resourceCount(it) > 0 }
+            .filter { if (state.isCk) CatanCk.goodsCount(state, it) > 0 else state.resourceCount(it) > 0 }
     }
 
     fun pirateMoves(state: CatanState, seat: Int): List<MovePirate> {
@@ -135,25 +135,168 @@ internal object SeaRules {
         val supply = Resource.entries.sumOf { CatanRules.bankSupply(state, it) }
         val queue = if (supply > 0) sea.gold else emptyList()
         return if (queue.isEmpty()) {
-            state.copy(sea = sea.copy(gold = emptyList()), phase = CatanPhase.PLAYING)
+            state.copy(sea = sea.copy(gold = emptyList(), afterGold = null), phase = sea.afterGold ?: CatanPhase.PLAYING)
         } else {
             state.copy(sea = sea.copy(gold = queue), phase = CatanPhase.GOLD)
         }
     }
 
+    // -----------------------------------------------------------------------
+    // Fog
+    // -----------------------------------------------------------------------
+
+    /** Hidden hexes a piece on [edge] reaches: any that touches either end. */
+    private fun fogReached(state: CatanState, edge: Int): List<Int> {
+        val topo = state.topo
+        return topo.EDGE_VERTICES[edge].toList()
+            .flatMap { topo.VERTEX_HEXES[it] }
+            .filter { state.terrains[it] == Terrain.FOG }
+            .distinct()
+            .sorted()
+    }
+
+    /**
+     * After a road or ship lands on [edge]: turn each fog hex it now touches face up. The finder takes one card
+     * of what it yields, or chooses any resource if it is gold, supply permitting. The caller's phase is kept.
+     */
+    fun reveal(state: CatanState, seat: Int, edge: Int): CatanState {
+        var s = state
+        val found = fogReached(state, edge)
+        if (found.isEmpty()) return s
+        val owed = mutableListOf<GoldOwed>()
+        for (hex in found) {
+            val sea = s.sea!!
+            val tile = sea.fogDeck.firstOrNull() ?: break
+            val name = tile.terrain.name.lowercase()
+            s = s.copy(
+                terrains = s.terrains.toMutableList().also { it[hex] = tile.terrain },
+                numbers = s.numbers.toMutableList().also { it[hex] = tile.number },
+                sea = sea.copy(fogDeck = sea.fogDeck.drop(1)),
+                log = s.log + "Seat $seat uncovers ${if (tile.terrain == Terrain.GOLD) "a gold field" else "the $name"} " +
+                    "(${s.topo.HEXES[hex].q},${s.topo.HEXES[hex].r})" +
+                    if (tile.number != 0) " with a ${tile.number}." else ".",
+            )
+            val resource = tile.terrain.produces
+            if (resource != null && CatanRules.bankSupply(s, resource) > 0) {
+                s = s.copy(resources = CatanRules.withCounts(s.resources, seat, mapOf(resource to 1), 1))
+            } else if (tile.terrain == Terrain.GOLD) {
+                owed += GoldOwed(seat, 1)
+            }
+        }
+        if (owed.isEmpty()) return s
+        return owe(s, seat, owed.sumOf { it.count })
+    }
+
+    /** Queues [count] cards of [seat]'s choice, to be taken before play resumes where it left off. */
+    private fun owe(state: CatanState, seat: Int, count: Int): CatanState {
+        val sea = state.sea!!
+        val queued = sea.copy(
+            gold = sea.gold + GoldOwed(seat, count),
+            afterGold = state.phase.takeIf { it != CatanPhase.GOLD } ?: sea.afterGold,
+        )
+        return settleGold(state.copy(sea = queued))
+    }
+
     // -----------------------------------------------------------------------
     // Islands and scoring
     // -----------------------------------------------------------------------
 
-    /** The bonus points [seat] holds for first landings. */
-    fun bonusPoints(state: CatanState, seat: Int): Int =
-        (state.sea?.islandBonus?.count { it == seat } ?: 0) * ISLAND_BONUS
+    /** The bonus points [seat] holds: first landings, tribe chips, and one for every two cloth. */
+    fun bonusPoints(state: CatanState, seat: Int): Int {
+        val sea = state.sea ?: return 0
+        return sea.islandBonus.count { it == seat } * ISLAND_BONUS +
+            clothOf(state, seat) / CLOTH_PER_POINT +
+            (sea.chipPoints.getOrNull(seat) ?: 0)
+    }
+
+    // -----------------------------------------------------------------------
+    // Cloth for Catan
+    // -----------------------------------------------------------------------
+
+    const val CLOTH_PER_POINT = 2
+
+    fun clothOf(state: CatanState, seat: Int): Int = state.sea?.cloth?.getOrNull(seat) ?: 0
+
+    /**
+     * After the dice pay: every village showing [number] pays one cloth to each settlement or city beside it
+     * (a city is not worth more here), until its stock runs out. A robber on the village stops it.
+     */
+    fun payCloth(state: CatanState, number: Int): CatanState {
+        val sea = state.sea ?: return state
+        if (sea.villageCloth.isEmpty()) return state
+        var s = state
+        val topo = state.topo
+        for (h in 0 until topo.HEX_COUNT) {
+            if (state.terrains[h] != Terrain.VILLAGE || state.numbers[h] != number || h == state.robber) continue
+            val takers = topo.HEX_CORNERS[h].mapNotNull { state.buildings[it]?.owner }
+            if (takers.isEmpty()) continue
+            // Seats in turn order from the roller get the last of the stock.
+            val order = takers.sortedBy { (it - state.turn + state.playerCount) % state.playerCount }
+            val current = s.sea!!
+            var stock = current.villageCloth[h]
+            val cloth = current.cloth.toMutableList()
+            val said = mutableListOf<String>()
+            for (seat in order) {
+                if (stock == 0) break
+                cloth[seat] += 1
+                stock--
+                said += "seat $seat"
+            }
+            if (said.isEmpty()) continue
+            val stocks = current.villageCloth.toMutableList().also { it[h] = stock }
+            s = s.copy(
+                sea = current.copy(cloth = cloth, villageCloth = stocks),
+                log = s.log + "The village at (${topo.HEXES[h].q},${topo.HEXES[h].r}) pays cloth to ${said.joinToString(", ")}.",
+            )
+        }
+        return s
+    }
+
+    // -----------------------------------------------------------------------
+    // The Forgotten Tribe
+    // -----------------------------------------------------------------------
+
+    /** After a settlement on [vertex]: take any tribe chip lying on a hex beside it. */
+    fun takeChips(state: CatanState, seat: Int, vertex: Int): CatanState {
+        var s = state
+        if (s.sea?.chips.isNullOrEmpty()) return s
+        var gold = 0
+        for (hex in state.topo.VERTEX_HEXES[vertex]) {
+            val sea = s.sea!!
+            val chip = sea.chips.getOrNull(hex) ?: continue
+            if (chip == TribeChip.NONE) continue
+            val rest = sea.chips.toMutableList().also { it[hex] = TribeChip.NONE }
+            var next = sea.copy(chips = rest)
+            val said = when (chip) {
+                TribeChip.POINT -> {
+                    val points = next.chipPoints.ifEmpty { List(state.playerCount) { 0 } }.toMutableList()
+                    points[seat] += 1
+                    next = next.copy(chipPoints = points)
+                    "a victory point"
+                }
+                TribeChip.HARBOUR -> {
+                    next = next.copy(harbourSeats = (next.harbourSeats + seat).distinct())
+                    "a harbour that trades 3:1"
+                }
+                else -> {
+                    gold += 2
+                    "two resources of its choice"
+                }
+            }
+            s = s.copy(sea = next, log = s.log + "Seat $seat takes the tribe's chip beside it: $said.")
+        }
+        return if (gold > 0) owe(s, seat, gold) else s
+    }
+
+    /** What happens to a new settlement of [seat]'s on [vertex] beyond the base game. */
+    fun settled(state: CatanState, seat: Int, vertex: Int): CatanState =
+        takeChips(claimIsland(state, seat, vertex), seat, vertex)
 
     /** After a settlement on [vertex]: award the island bonus if it is the first on a new island. */
     fun claimIsland(state: CatanState, seat: Int, vertex: Int): CatanState {
         val sea = state.sea ?: return state
         val island = state.topo.vertexIsland[vertex]
-        if (island < 0 || island == sea.home || sea.islandBonus[island] != NO_PLAYER) return state
+        if (island < 0 || sea.isStart(island) || sea.islandBonus[island] != NO_PLAYER) return state
         val bonus = sea.islandBonus.toMutableList().also { it[island] = seat }
         return state.copy(
             sea = sea.copy(islandBonus = bonus),

app/src/main/java/org/prolibertate/games/game/mastermind/MastermindAi.kt

@@ -1,6 +1,7 @@
 package org.prolibertate.games.game.mastermind
 
 import kotlin.random.Random
+import org.prolibertate.games.game.engine.AiLevel
 import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
@@ -18,15 +19,13 @@ import org.prolibertate.games.game.engine.GameAi
  *   plays the one whose *worst* possible answer leaves the smallest number of
  *   candidates behind, so it cannot be given a reply that tells it little.
  *
- * The table already carries its own three-step level ([MastermindOptions.level]),
- * chosen at setup and shown to the player, and it means exactly what an
- * [org.prolibertate.games.game.engine.AiLevel] would here. Layering a second
- * knob on top would make the two disagree, so the shared [profiles] are
- * accepted for a uniform constructor but this game keeps playing at the level
- * the table names. [level] overrides that, which is what the tests use.
+ * The computer difficulty chosen at setup picks the level: Easy plays Casual,
+ * Medium plays whatever the table's saved [MastermindOptions.level] says (Club
+ * for a new game) and Hard plays Strong. [level] overrides all of that, which is
+ * what the tests use.
  */
 class MastermindAi(
-    @Suppress("unused") private val profiles: AiProfiles = AiProfiles.DEFAULT,
+    private val profiles: AiProfiles = AiProfiles.DEFAULT,
     private val level: MastermindLevel? = null,
 ) : GameAi<MastermindState, MastermindMove> {
 
@@ -38,7 +37,12 @@ class MastermindAi(
         legal: List<MastermindMove>,
     ): MastermindMove {
         require(legal.isNotEmpty()) { "No legal guess for seat $seat" }
-        val setting = level ?: state.options.level
+        val profile = profiles.of(seat)
+        val setting = level ?: when (profile.level) {
+            AiLevel.EASY -> MastermindLevel.CASUAL
+            AiLevel.MEDIUM -> state.options.level
+            AiLevel.HARD -> MastermindLevel.STRONG
+        }
 
         // Deterministic for a given position, so a host and a client watching
         // the same game agree on what the computer did.

app/src/main/java/org/prolibertate/games/ui/GameSetupScreen.kt

@@ -35,11 +35,8 @@ import org.prolibertate.games.game.engine.PlayerKind
 import org.prolibertate.games.game.engine.PlayerSlot
 import org.prolibertate.games.game.engine.SavedMatch
 import org.prolibertate.games.game.engine.TableConfig
-import org.prolibertate.games.game.backgammon.BackgammonLevel
 import org.prolibertate.games.game.backgammon.BackgammonOptions
-import org.prolibertate.games.game.checkers.CheckersLevel
 import org.prolibertate.games.game.checkers.CheckersOptions
-import org.prolibertate.games.game.chess.ChessLevel
 import org.prolibertate.games.game.chess.ChessOptions
 import org.prolibertate.games.game.crazyeights.CrazyEightsOptions
 import org.prolibertate.games.game.cribbage.CribbageOptions
@@ -57,15 +54,13 @@ import org.prolibertate.games.game.pegsolitaire.PegBoard
 import org.prolibertate.games.game.pegsolitaire.PegGoal
 import org.prolibertate.games.game.pegsolitaire.PegSolitaireOptions
 import org.prolibertate.games.game.kaiser.KaiserOptions
-import org.prolibertate.games.game.mastermind.MastermindLevel
 import org.prolibertate.games.game.mastermind.MastermindOptions
-import org.prolibertate.games.game.morris.MorrisLevel
 import org.prolibertate.games.game.morris.MorrisOptions
-import org.prolibertate.games.game.pirates.PiratesLevel
 import org.prolibertate.games.game.pirates.PiratesOptions
 import org.prolibertate.games.game.president.PresidentOptions
 import org.prolibertate.games.game.catan.CatanOptions
-import org.prolibertate.games.game.catan.CatanRuleSet
+import org.prolibertate.games.game.catan.CatanExpansion
+import org.prolibertate.games.game.catan.SeaScenario
 import org.prolibertate.games.game.sequence.SequenceOptions
 import org.prolibertate.games.game.tayu.TayuLevel
 import org.prolibertate.games.game.tayu.TayuOptions
@@ -379,47 +374,50 @@ fun teamForSeat(gameId: String, seat: Int, seatCount: Int): Int = when (gameId)
     else -> seat
 }
 
-/** The targets the setup screen offers for a Katan rule set. */
-internal fun catanPointsChoices(ruleSet: CatanRuleSet): List<Int> = when (ruleSet) {
-    // Five is a short game for trying things out; ten is the published target.
-    CatanRuleSet.BASE -> listOf(5, 8, 10, 12)
-    // Cities & Knights is played to thirteen, which is also why it runs longer.
-    CatanRuleSet.CITIES_AND_KNIGHTS -> listOf(8, 10, 13, 15)
+/** The targets the setup screen offers for a Katan game with [expansions] on. */
+internal fun catanPointsChoices(expansions: Set<CatanExpansion>): List<Int> = when {
+    // Both: Cities & Knights' long game plus the new-island points.
+    expansions.size > 1 -> listOf(10, 12, 14, 16)
     // Seafarers adds two points for each new island, so the target is higher.
-    CatanRuleSet.SEAFARERS -> listOf(8, 10, 12, 14)
+    CatanExpansion.SEAFARERS in expansions -> listOf(8, 10, 12, 14)
+    // Cities & Knights is played to thirteen, which is also why it runs longer.
+    CatanExpansion.CITIES_AND_KNIGHTS in expansions -> listOf(8, 10, 13, 15)
+    // Five is a short game for trying things out; ten is the published target.
+    else -> listOf(5, 8, 10, 12)
 }
 
-/** The published target for a rule set. */
-internal fun catanDefaultPoints(ruleSet: CatanRuleSet): Int = when (ruleSet) {
-    CatanRuleSet.BASE -> 10
-    CatanRuleSet.CITIES_AND_KNIGHTS -> 13
-    CatanRuleSet.SEAFARERS -> 12
+/** The published target for a game with [expansions] on. */
+internal fun catanDefaultPoints(expansions: Set<CatanExpansion>): Int = when {
+    expansions.size > 1 -> 14
+    CatanExpansion.SEAFARERS in expansions -> 12
+    CatanExpansion.CITIES_AND_KNIGHTS in expansions -> 13
+    else -> 10
 }
 
 /**
- * [options] switched to [ruleSet]. The target moves to the new rule set's own
+ * [options] with [expansion] switched on or off. The target moves to the new combination's own
  * default unless the one already chosen is on its menu too.
  */
-internal fun catanSwitchRules(options: CatanOptions, ruleSet: CatanRuleSet): CatanOptions =
-    options.copy(
-        ruleSet = ruleSet,
-        pointsToWin = options.pointsToWin.takeIf { it in catanPointsChoices(ruleSet) && it != catanDefaultPoints(options.ruleSet) }
-            ?: catanDefaultPoints(ruleSet),
+internal fun catanToggleExpansion(options: CatanOptions, expansion: CatanExpansion, on: Boolean): CatanOptions {
+    val expansions = if (on) options.expansions + expansion else options.expansions - expansion
+    return options.copy(
+        expansions = expansions,
+        pointsToWin = options.pointsToWin.takeIf {
+            it in catanPointsChoices(expansions) && it != catanDefaultPoints(options.expansions)
+        } ?: catanDefaultPoints(expansions),
     )
-
-private fun catanRuleSetName(ruleSet: CatanRuleSet): String = when (ruleSet) {
-    CatanRuleSet.BASE -> "Base game"
-    CatanRuleSet.CITIES_AND_KNIGHTS -> "Cities & Knights"
-    CatanRuleSet.SEAFARERS -> "Seafarers"
 }
 
-private fun catanRuleSetBlurb(ruleSet: CatanRuleSet): String = when (ruleSet) {
-    CatanRuleSet.BASE ->
-        "Settle the island, trade, and play development cards. Longest Road and Largest Army score."
-    CatanRuleSet.CITIES_AND_KNIGHTS ->
+private fun catanExpansionName(expansion: CatanExpansion): String = when (expansion) {
+    CatanExpansion.CITIES_AND_KNIGHTS -> "Cities & Knights"
+    CatanExpansion.SEAFARERS -> "Seafarers"
+}
+
+private fun catanExpansionBlurb(expansion: CatanExpansion): String = when (expansion) {
+    CatanExpansion.CITIES_AND_KNIGHTS ->
         "Cities make commodities, knights hold off the barbarians, and improvements earn progress " +
             "cards and metropolises. No development cards; the robber sleeps until the first attack."
-    CatanRuleSet.SEAFARERS ->
+    CatanExpansion.SEAFARERS ->
         "Build ships to reach new islands. Gold fields pay any resource, a pirate guards the sea, " +
             "and the first settlement on each new island scores two extra points."
 }
@@ -427,14 +425,24 @@ private fun catanRuleSetBlurb(ruleSet: CatanRuleSet): String = when (ruleSet) {
 @Composable
 private fun CatanOptionsEditor(options: CatanOptions, onChange: (CatanOptions) -> Unit) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
-        ChipRow(
-            label = "Rules",
-            values = CatanRuleSet.entries,
-            selected = options.ruleSet,
-            display = ::catanRuleSetName,
-            onSelect = { onChange(catanSwitchRules(options, it)) },
-        )
-        Text(catanRuleSetBlurb(options.ruleSet), style = MaterialTheme.typography.bodySmall)
+        CatanExpansion.entries.forEach { expansion ->
+            ToggleRow(
+                title = catanExpansionName(expansion),
+                subtitle = catanExpansionBlurb(expansion),
+                checked = expansion in options.expansions,
+                onChange = { onChange(catanToggleExpansion(options, expansion, it)) },
+            )
+        }
+        if (options.seafarers) {
+            ChipRow(
+                label = "Map",
+                values = SeaScenario.entries,
+                selected = options.scenario,
+                display = { it.title },
+                onSelect = { onChange(options.copy(scenario = it)) },
+            )
+            Text(options.scenario.blurb, style = MaterialTheme.typography.bodySmall)
+        }
         ChipRow(
             label = "Players",
             values = listOf(3, 4),
@@ -444,7 +452,7 @@ private fun CatanOptionsEditor(options: CatanOptions, onChange: (CatanOptions) -
         )
         ChipRow(
             label = "Game to",
-            values = catanPointsChoices(options.ruleSet),
+            values = catanPointsChoices(options.expansions),
             selected = options.pointsToWin,
             display = { "$it points" },
             onSelect = { onChange(options.copy(pointsToWin = it)) },
@@ -785,13 +793,6 @@ private fun ChessOptionsEditor(
             display = { if (it) "White" else "Black" },
             onSelect = onColour,
         )
-        ChipRow(
-            label = "Opponent",
-            values = ChessLevel.entries.toList(),
-            selected = options.level,
-            display = { it.label },
-            onSelect = { onChange(options.copy(level = it)) },
-        )
         ToggleRow(
             title = "Fifty-move rule",
             subtitle = "Fifty moves each with no capture and no pawn move is a draw",
@@ -815,13 +816,6 @@ private fun ChessOptionsEditor(
 @Composable
 private fun CheckersOptionsEditor(options: CheckersOptions, onChange: (CheckersOptions) -> Unit) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
-        ChipRow(
-            label = "Opponent",
-            values = CheckersLevel.entries.toList(),
-            selected = options.level,
-            display = { it.label },
-            onSelect = { onChange(options.copy(level = it)) },
-        )
         ToggleRow(
             title = "Flying kings",
             subtitle = "A king slides the length of a diagonal and takes from a distance, " +
@@ -856,13 +850,6 @@ private fun BackgammonOptionsEditor(
     onChange: (BackgammonOptions) -> Unit,
 ) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
-        ChipRow(
-            label = "Opponent",
-            values = BackgammonLevel.entries.toList(),
-            selected = options.level,
-            display = { it.label },
-            onSelect = { onChange(options.copy(level = it)) },
-        )
         ToggleRow(
             title = "Count gammons",
             subtitle = "A loser who bore nothing off has lost double, and one still on the " +
@@ -884,13 +871,6 @@ private fun MastermindOptionsEditor(
     onChange: (MastermindOptions) -> Unit,
 ) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
-        ChipRow(
-            label = "Opponent",
-            values = MastermindLevel.entries.toList(),
-            selected = options.level,
-            display = { it.label },
-            onSelect = { onChange(options.copy(level = it)) },
-        )
         ChipRow(
             label = "Colours",
             values = listOf(6, 8),
@@ -955,13 +935,6 @@ private fun PiratesOptionsEditor(
             display = { if (it) "the two pirates" else "the twenty-four Bulgars" },
             onSelect = onSide,
         )
-        ChipRow(
-            label = "Opponent",
-            values = PiratesLevel.entries.toList(),
-            selected = options.level,
-            display = { it.label },
-            onSelect = { onChange(options.copy(level = it)) },
-        )
         ToggleRow(
             title = "A pirate who can take must take",
             subtitle = "The rule that huffing exists to enforce, applied directly",
@@ -987,13 +960,6 @@ private fun PiratesOptionsEditor(
 @Composable
 private fun MorrisOptionsEditor(options: MorrisOptions, onChange: (MorrisOptions) -> Unit) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
-        ChipRow(
-            label = "Opponent",
-            values = MorrisLevel.entries.toList(),
-            selected = options.level,
-            display = { it.label },
-            onSelect = { onChange(options.copy(level = it)) },
-        )
         ChipRow(
             label = "Pieces each",
             values = listOf(3, 6, 9),

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanBoardView.kt

@@ -34,6 +34,7 @@ import org.prolibertate.games.game.catan.CatanState
 import org.prolibertate.games.game.catan.NO_PLAYER
 import org.prolibertate.games.game.catan.Resource
 import org.prolibertate.games.game.catan.Terrain
+import org.prolibertate.games.game.catan.TribeChip
 
 /**
  * The island, drawn and tappable.
@@ -156,6 +157,36 @@ private fun DrawScope.drawHexes(
 
         val number = state.numbers[hex]
         if (number != 0) drawToken(number, centre, board, style, measurer)
+        if (state.terrains[hex] == Terrain.FOG) {
+            drawCentered(
+                measurer = measurer,
+                text = "?",
+                at = centre,
+                fontPx = board.radius * 0.9f,
+                color = style.hexEdge.copy(alpha = 0.7f),
+                weight = FontWeight.Bold,
+            )
+        }
+        val sea = state.sea
+        val note = when {
+            state.terrains[hex] == Terrain.VILLAGE && sea != null -> "${sea.villageCloth.getOrElse(hex) { 0 }} cloth"
+            else -> when (sea?.chips?.getOrNull(hex)) {
+                TribeChip.POINT -> "+1 VP"
+                TribeChip.HARBOUR -> "3:1"
+                TribeChip.GOLD -> "gold"
+                else -> null
+            }
+        }
+        if (note != null) {
+            drawCentered(
+                measurer = measurer,
+                text = note,
+                at = Pt(centre.x, centre.y + board.radius * 0.62f),
+                fontPx = board.radius * 0.26f,
+                color = style.tokenInk,
+                weight = FontWeight.Bold,
+            )
+        }
     }
 }
 

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanPanels.kt

@@ -256,6 +256,7 @@ fun CatanPlayerCard(
                     if (at.seat == seat) add(if (compact) track.name.first().toString() else "${CatanText.track(track)} metropolis")
                 }
                 if (ck.merchant?.seat == seat) add("Merchant")
+                addAll(seaAwards(state, seat, compact))
             }
             CardLine(
                 text = ckAwards.joinToString(" · ").ifEmpty { BLANK },
@@ -280,6 +281,7 @@ fun CatanPlayerCard(
         val awards = buildList {
             if (state.longestRoadOwner == seat) add(if (compact) "Road" else "Longest road")
             if (state.largestArmyOwner == seat) add(if (compact) "Army" else "Largest army")
+            addAll(seaAwards(state, seat, compact))
         }
         // Always drawn, so the card does not grow when somebody takes an award.
         CardLine(
@@ -634,3 +636,12 @@ fun CatanLog(state: CatanState, modifier: Modifier = Modifier) {
         }
     }
 }
+
+/** Seafarers scenario holdings worth a word on a player's card: cloth, and a tribe harbour. */
+private fun seaAwards(state: CatanState, seat: Int, compact: Boolean): List<String> {
+    val sea = state.sea ?: return emptyList()
+    return buildList {
+        if (sea.cloth.isNotEmpty()) add(if (compact) "${sea.cloth[seat]}c" else "Cloth ${sea.cloth[seat]}")
+        if (seat in sea.harbourSeats) add(if (compact) "3:1" else "Harbour 3:1")
+    }
+}

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanScreen.kt

@@ -198,7 +198,7 @@ fun CatanScreen(
     val playing = current.phase == CatanPhase.PLAYING && legal.isNotEmpty()
     val actions = CatanActions(
         buildKinds = when {
-            current.isCk -> BuildKind.entries.filter { it != BuildKind.SHIP }
+            current.isCk -> BuildKind.entries.filter { it != BuildKind.SHIP || current.isSea }
             current.isSea -> BuildKind.SEAFARERS
             else -> BuildKind.BASE
         },

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanStyle.kt

@@ -124,6 +124,10 @@ private val LightStyle = CatanStyle(
         // Seafarers. Sea hexes are drawn as a faint wash over the water; gold is a rich yellow.
         Terrain.SEA to Color(0xFF3A7CA5),
         Terrain.GOLD to Color(0xFFF2B01E),
+        // Land not yet found: a pale grey bank of fog with a question mark.
+        Terrain.FOG to Color(0xFFB9C2C9),
+        // Cloth villages: a dyed-cloth purple.
+        Terrain.VILLAGE to Color(0xFF9B6BB5),
     ),
     hexEdge = Color(0x55000000),
     token = Color(0xFFF7EFD9),

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanText.kt

@@ -74,6 +74,8 @@ object CatanText {
         Terrain.DESERT -> "Desert"
         Terrain.SEA -> "Sea"
         Terrain.GOLD -> "Gold field"
+        Terrain.FOG -> "Fog"
+        Terrain.VILLAGE -> "Village"
     }
 
     fun devCard(type: DevCardType): String = when (type) {
@@ -193,7 +195,7 @@ object CatanText {
         /** Seafarers: a ship has been picked to sail, and its destination is awaited. */
         movingShip: Boolean = false,
     ): String {
-        if (state.isCk) return ckPrompt(state, seats, setupVertexChosen, building, movingKnight, armed)
+        if (state.isCk) return ckPrompt(state, seats, setupVertexChosen, building, movingKnight, armed, movingShip)
         val me = seats.me
         val onClock = CatanRules.currentSeat(state)
         val mine = onClock == me
@@ -400,6 +402,7 @@ object CatanText {
         building: BuildKind?,
         movingKnight: Boolean,
         armed: ProgressType?,
+        movingShip: Boolean,
     ): String {
         val me = seats.me
         val onClock = CatanRules.currentSeat(state)
@@ -408,7 +411,12 @@ object CatanText {
         val ck = state.ck!!
 
         return when (state.phase) {
-            CatanPhase.GOLD -> ""
+            CatanPhase.GOLD ->
+                if (mine) {
+                    "Gold! Choose ${state.sea?.gold?.firstOrNull()?.count ?: 1} resource cards."
+                } else {
+                    "${seats.label(onClock ?: state.turn)} is choosing from the gold…"
+                }
 
             CatanPhase.GAME_OVER -> {
                 val winner = state.winner
@@ -434,6 +442,7 @@ object CatanText {
             CatanPhase.ROBBER -> when {
                 !mine -> "$turn is moving the robber…"
                 ck.bishop -> "The bishop: tap a hex. Everyone beside it pays you a card."
+                state.isSea -> SEA_ROBBER
                 else -> "Move the robber. Tap a hex."
             }
 
@@ -441,6 +450,8 @@ object CatanText {
                 !mine -> "$turn is playing…"
                 armed != null -> armedPrompt(armed)
                 movingKnight -> "Tap where the knight should go."
+                movingShip -> "Tap the sea edge to sail the ship to."
+                building == BuildKind.SHIP -> "Tap a sea edge beside your fleet or a harbour town to launch a ship."
                 building == BuildKind.ROAD -> "Tap an edge to build a road."
                 building == BuildKind.SETTLEMENT -> "Tap an empty crossing to build a settlement."
                 building == BuildKind.CITY -> "Tap one of your settlements to upgrade it."

app/src/test/java/org/prolibertate/games/game/catan/CatanAiProfilesTest.kt

@@ -55,15 +55,15 @@ class CatanAiProfilesTest {
             (0 until 3).any { p.of(it).style == style }
         }
 
-    private fun forEveryProfile(rules: CatanRuleSet, cap: Int) {
+    private fun forEveryProfile(rules: Set<CatanExpansion>, cap: Int) {
         val options = CatanOptions(
             playerCount = 3,
-            pointsToWin = when (rules) {
-                CatanRuleSet.BASE -> 10
-                CatanRuleSet.CITIES_AND_KNIGHTS -> 13
-                else -> 12
+            pointsToWin = when {
+                CatanExpansion.CITIES_AND_KNIGHTS in rules -> 13
+                CatanExpansion.SEAFARERS in rules -> 12
+                else -> 10
             },
-            ruleSet = rules,
+            expansions = rules,
         )
         for (difficulty in listOf(AiDifficulty.EASY, AiDifficulty.HARD)) {
             for (style in AiStyle.entries) {
@@ -78,14 +78,14 @@ class CatanAiProfilesTest {
     }
 
     @Test
-    fun `easy and hard seats of every style play the base game`() = forEveryProfile(CatanRuleSet.BASE, 1_500)
+    fun `easy and hard seats of every style play the base game`() = forEveryProfile(emptySet(), 1_500)
 
     @Test
     fun `easy and hard seats of every style play Cities and Knights`() =
-        forEveryProfile(CatanRuleSet.CITIES_AND_KNIGHTS, 1_500)
+        forEveryProfile(setOf(CatanExpansion.CITIES_AND_KNIGHTS), 1_500)
 
     @Test
-    fun `easy and hard seats of every style play Seafarers`() = forEveryProfile(CatanRuleSet.SEAFARERS, 1_500)
+    fun `easy and hard seats of every style play Seafarers`() = forEveryProfile(setOf(CatanExpansion.SEAFARERS), 1_500)
 
     @Test
     fun `a mixed table of four finishes a base game`() {
@@ -95,8 +95,8 @@ class CatanAiProfilesTest {
 
     @Test
     fun `the default profile plays exactly as an explicit medium table does`() {
-        for (rules in listOf(CatanRuleSet.BASE, CatanRuleSet.CITIES_AND_KNIGHTS)) {
-            val options = CatanOptions(playerCount = 3, pointsToWin = 10, ruleSet = rules)
+        for (rules in listOf(emptySet(), setOf(CatanExpansion.CITIES_AND_KNIGHTS))) {
+            val options = CatanOptions(playerCount = 3, pointsToWin = 10, expansions = rules)
             val plain = play(options, 9L, AiProfiles.DEFAULT, 600)
             val medium = play(options, 9L, AiProfiles(AiDifficulty.MEDIUM, 1234L), 600)
             assertEquals("$rules", plain, medium)

app/src/test/java/org/prolibertate/games/game/catan/CatanCkRulesTest.kt

@@ -25,7 +25,7 @@ class CatanCkRulesTest {
             CatanOptions(
                 playerCount = players,
                 pointsToWin = 13,
-                ruleSet = if (ck) CatanRuleSet.CITIES_AND_KNIGHTS else CatanRuleSet.BASE,
+                expansions = if (ck) setOf(CatanExpansion.CITIES_AND_KNIGHTS) else emptySet(),
             ),
         ),
         seed = seed,
@@ -138,7 +138,7 @@ class CatanCkRulesTest {
         val base = CatanRules.initialState(config(ck = false))
         assertNull(base.ck)
         assertEquals(25, base.devDeck.size)
-        assertEquals(CatanRuleSet.BASE, base.options.ruleSet)
+        assertEquals(emptySet<CatanExpansion>(), base.options.expansions)
     }
 
     @Test
@@ -157,7 +157,21 @@ class CatanCkRulesTest {
     fun `the options without a rule set still read as the base game`() {
         val old = """{"playerCount":4,"pointsToWin":10}"""
         val options = Json { ignoreUnknownKeys = true }.decodeFromString<CatanOptions>(old)
-        assertEquals(CatanRuleSet.BASE, options.ruleSet)
+        assertEquals(emptySet<CatanExpansion>(), options.expansions)
+    }
+
+    @Test
+    fun `options saved with a rule set still read as the expansion they named`() {
+        val read = { text: String -> Json { ignoreUnknownKeys = true }.decodeFromString<CatanOptions>(text) }
+        assertEquals(
+            setOf(CatanExpansion.CITIES_AND_KNIGHTS),
+            read("""{"playerCount":3,"pointsToWin":13,"ruleSet":"CITIES_AND_KNIGHTS"}""").expansions,
+        )
+        assertEquals(
+            setOf(CatanExpansion.SEAFARERS),
+            read("""{"playerCount":3,"pointsToWin":12,"ruleSet":"SEAFARERS"}""").expansions,
+        )
+        assertEquals(emptySet<CatanExpansion>(), read("""{"ruleSet":"BASE"}""").expansions)
     }
 
     @Test

app/src/test/java/org/prolibertate/games/game/catan/CatanCkSelfPlayTest.kt

@@ -152,7 +152,7 @@ class CatanCkSelfPlayTest {
     fun `three engines play Cities and Knights to a finish`() {
         val reports = (1L..12L).map { seed ->
             val (state, report) = playOut(
-                CatanOptions(playerCount = 3, pointsToWin = 13, ruleSet = CatanRuleSet.CITIES_AND_KNIGHTS),
+                CatanOptions(playerCount = 3, pointsToWin = 13, expansions = setOf(CatanExpansion.CITIES_AND_KNIGHTS)),
                 seed,
             )
             assertEquals("seed $seed", CatanPhase.GAME_OVER, state.phase)
@@ -171,7 +171,7 @@ class CatanCkSelfPlayTest {
     fun `four engines play Cities and Knights to a finish`() {
         val reports = (101L..108L).map { seed ->
             val (state, report) = playOut(
-                CatanOptions(playerCount = 4, pointsToWin = 13, ruleSet = CatanRuleSet.CITIES_AND_KNIGHTS),
+                CatanOptions(playerCount = 4, pointsToWin = 13, expansions = setOf(CatanExpansion.CITIES_AND_KNIGHTS)),
                 seed,
             )
             assertEquals("seed $seed", CatanPhase.GAME_OVER, state.phase)

app/src/test/java/org/prolibertate/games/game/catan/CatanRulesTest.kt

@@ -115,8 +115,9 @@ class CatanRulesTest {
     // -- Setup ---------------------------------------------------------------
 
     @Test
-    fun `setup runs in snake order and then seat zero leads`() {
+    fun `setup runs in snake order from the first seat and then that seat leads`() {
         var state = CatanRules.initialState(config())
+        val first = state.firstSeat
         val order = mutableListOf<Int>()
         while (state.phase == CatanPhase.SETUP_FIRST || state.phase == CatanPhase.SETUP_SECOND) {
             val seat = CatanRules.currentSeat(state)!!
@@ -126,12 +127,21 @@ class CatanRulesTest {
                 CatanRules.legalMoves(state, seat).filterIsInstance<SetupPlace>().first(),
             )
         }
-        assertEquals(listOf(0, 1, 2, 2, 1, 0), order)
+        val forward = (0 until 3).map { (first + it) % 3 }
+        assertEquals(forward + forward.reversed(), order)
         assertEquals(CatanPhase.AWAIT_ROLL, state.phase)
-        assertEquals(0, state.turn)
+        assertEquals(first, state.turn)
         assertEquals(1, state.turnNumber)
     }
 
+    @Test
+    fun `the first seat comes from the seed and varies between tables`() {
+        val firsts = (1L..40L).map { CatanRules.initialState(config(seed = it)).firstSeat }
+        assertEquals(firsts, (1L..40L).map { CatanRules.initialState(config(seed = it)).firstSeat })
+        assertEquals(setOf(0, 1, 2), firsts.toSet())
+        assertEquals(firsts[0], CatanRules.initialState(config(seed = 1L)).turn)
+    }
+
     @Test
     fun `the second settlement earns one card from each adjacent land`() {
         var state = CatanRules.initialState(config())

app/src/test/java/org/prolibertate/games/game/catan/CatanSeaCkTest.kt

@@ -0,0 +1,154 @@
+package org.prolibertate.games.game.catan
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+/** Cities & Knights played on a Seafarers map. */
+class CatanSeaCkTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun options(scenario: SeaScenario = SeaScenario.NEW_SHORES, players: Int = 3) = CatanOptions(
+        playerCount = players,
+        pointsToWin = 14,
+        expansions = setOf(CatanExpansion.CITIES_AND_KNIGHTS, CatanExpansion.SEAFARERS),
+        scenario = scenario,
+    )
+
+    private fun config(options: CatanOptions, seed: Long) = TableConfig(
+        gameId = GameCatalog.CATAN,
+        seats = (0 until options.playerCount).map {
+            PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it)
+        },
+        optionsJson = json.encodeToString(options),
+        seed = seed,
+    )
+
+    private fun start(scenario: SeaScenario = SeaScenario.NEW_SHORES, seed: Long = 7L) =
+        CatanRules.initialState(config(options(scenario), seed))
+
+    private fun CatanState.city(vertex: Int, seat: Int) =
+        copy(buildings = buildings.toMutableList().also { it[vertex] = CatanBuilding(BuildingType.CITY, seat) })
+
+    @Test
+    fun `both expansions switch on together and the state carries both`() {
+        val s = start()
+        assertNotNull(s.ck)
+        assertNotNull(s.sea)
+        assertTrue(s.devDeck.isEmpty())
+        assertEquals(setOf(CatanExpansion.CITIES_AND_KNIGHTS, CatanExpansion.SEAFARERS), s.options.expansions)
+        assertEquals(s, CatanRules.decodeState(CatanRules.encodeState(s)))
+    }
+
+    @Test
+    fun `a ship is on offer in play, and a knight can stand at the end of a ship route on land`() {
+        val s0 = start()
+        val topo = s0.topo
+        // A coastal home town with a sea edge leaving it.
+        val town = (0 until topo.VERTEX_COUNT).first { v ->
+            topo.vertexIsland[v] == s0.sea!!.home &&
+                topo.VERTEX_EDGES[v].any { topo.edgeSea[it] && !topo.edgeLand[it] }
+        }
+        val s = s0.city(town, 0).copy(
+            phase = CatanPhase.PLAYING, turn = 0, turnNumber = 3,
+            resources = List(3) { Resource.entries.associateWith { 5 } },
+        )
+        val moves = CatanRules.legalMoves(s, 0)
+        assertTrue("no ship on offer", moves.any { it is BuildShip })
+        assertTrue("sea vertices are never knight posts", moves.filterIsInstance<HireKnight>().all { topo.vertexLand[it.vertex] })
+    }
+
+    @Test
+    fun `a gold field pays its owner a choice after the roll, then play goes on`() {
+        val s0 = start()
+        val topo = s0.topo
+        val gold = s0.terrains.indexOf(Terrain.GOLD)
+        val number = s0.numbers[gold]
+        val vertex = topo.HEX_CORNERS[gold].first { topo.vertexLand[it] }
+        val dice = (1..6).flatMap { a -> (1..6).map { b -> listOf(a, b) } }.first { it.sum() == number }
+        val s = s0.city(vertex, 0).copy(phase = CatanPhase.AWAIT_ROLL, turn = 0, turnNumber = 3, robber = 0)
+        val rolled = CatanRules.applyMove(s, 0, RollDice(forced = dice, event = EventFace.TRADE))
+        assertEquals(CatanPhase.GOLD, rolled.phase)
+        assertEquals(listOf(GoldOwed(0, 2)), rolled.sea!!.gold)
+        val pick = CatanRules.legalMoves(rolled, 0).filterIsInstance<PickGold>().first { it.cards == listOf(Resource.ORE, Resource.ORE) }
+        val after = CatanRules.applyMove(rolled, 0, pick)
+        assertEquals(CatanPhase.PLAYING, after.phase)
+        assertEquals(2, after.resources[0].getValue(Resource.ORE) - s.resources[0].getValue(Resource.ORE))
+    }
+
+    @Test
+    fun `once the barbarians have landed a seven may send the pirate, which robs goods`() {
+        val s0 = start()
+        val topo = s0.topo
+        val seaHex = (0 until topo.HEX_COUNT).first { !topo.land[it] && it != s0.sea!!.pirate &&
+            (0 until topo.EDGE_COUNT).any { e -> it in topo.EDGE_HEXES[e] && topo.edgeLand[e] } }
+        val edge = (0 until topo.EDGE_COUNT).first { seaHex in topo.EDGE_HEXES[it] }
+        val s = s0.copy(
+            phase = CatanPhase.ROBBER, turn = 0, turnNumber = 3,
+            ck = s0.ck!!.copy(attacked = true),
+            sea = s0.sea!!.copy(ships = s0.sea!!.ships.toMutableList().also { it[edge] = 1 }),
+            resources = s0.resources.toMutableList().also { it[1] = it[1] + (Resource.GRAIN to 2) },
+        )
+        val pirate = CatanRules.legalMoves(s, 0).filterIsInstance<MovePirate>()
+            .first { it.hex == topo.HEXES[seaHex] && it.victim == 1 }
+        val after = CatanRules.applyMove(s, 0, pirate)
+        assertEquals(seaHex, after.sea!!.pirate)
+        assertEquals(CatanPhase.PLAYING, after.phase)
+        assertEquals(CatanCk.goodsCount(s, 0) + 1, CatanCk.goodsCount(after, 0))
+        assertEquals(CatanCk.goodsCount(s, 1) - 1, CatanCk.goodsCount(after, 1))
+        // The robber itself is kept off the sea and the fog.
+        val robber = CatanRules.legalMoves(s, 0).filterIsInstance<MoveRobber>()
+        assertTrue(robber.all { topo.land[topo.hexIndex.getValue(it.hex)] })
+    }
+
+    @Test
+    fun `first landings count toward the target`() {
+        val s0 = start()
+        val sea = s0.sea!!
+        val islet = (0 until s0.topo.islandCount).first { !sea.isStart(it) }
+        val withBonus = s0.copy(sea = sea.copy(islandBonus = sea.islandBonus.toMutableList().also { it[islet] = 2 }))
+        assertEquals(CatanCk.publicVictoryPoints(s0)[2] + SeaRules.ISLAND_BONUS, CatanCk.publicVictoryPoints(withBonus)[2])
+    }
+
+    @Test
+    fun `engines finish a Cities and Knights game on three maps`() {
+        var ships = 0
+        var knights = 0
+        var barbarianAttacks = 0
+        for ((scenario, players, seed) in listOf(
+            Triple(SeaScenario.NEW_SHORES, 3, 21L),
+            Triple(SeaScenario.FOUR_ISLANDS, 4, 22L),
+            Triple(SeaScenario.FOG_ISLANDS, 3, 23L),
+        )) {
+            val ai = CatanAi()
+            var state = CatanRules.initialState(config(options(scenario, players), seed))
+            var moves = 0
+            while (!CatanRules.isFinished(state)) {
+                assertTrue("$scenario seed $seed ran past the cap; log: ${state.log.takeLast(6)}", moves++ < 40_000)
+                val seat = CatanRules.currentSeat(state) ?: error("$scenario: nobody to move in ${state.phase}; ${state.log.takeLast(4)}")
+                val legal = CatanRules.legalMoves(state, seat)
+                assertTrue("$scenario: no legal move for $seat in ${state.phase}", legal.isNotEmpty())
+                val move = ai.chooseMove(state, seat, legal)
+                assertTrue("$scenario: illegal $move in ${state.phase}", CatanRules.isLegalMove(state, seat, move))
+                state = CatanRules.applyMove(state, seat, move)
+                if (moves % 40 == 0) assertEquals(state, CatanRules.decodeState(CatanRules.encodeState(state)))
+            }
+            assertFalse(state.winner == null)
+            ships += state.sea!!.ships.count { it != NO_PLAYER }
+            knights += state.ck!!.knights.size
+            if (state.ck!!.attacked) barbarianAttacks++
+        }
+        assertTrue("no ships were built", ships > 0)
+        assertTrue("no knights were hired", knights > 0)
+        assertTrue("the barbarians never landed", barbarianAttacks > 0)
+    }
+}

app/src/test/java/org/prolibertate/games/game/catan/CatanSeaExtrasTest.kt

@@ -0,0 +1,168 @@
+package org.prolibertate.games.game.catan
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+/** The scenarios with rules of their own: cloth villages and tribe chips. */
+class CatanSeaExtrasTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun start(scenario: SeaScenario, seed: Long = 5L, players: Int = 3): CatanState {
+        val options = CatanOptions(
+            playerCount = players,
+            pointsToWin = 14,
+            expansions = setOf(CatanExpansion.SEAFARERS),
+            scenario = scenario,
+        )
+        val config = TableConfig(
+            gameId = GameCatalog.CATAN,
+            seats = (0 until players).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
+            optionsJson = json.encodeToString(options),
+            seed = seed,
+        )
+        return CatanRules.initialState(config).copy(phase = CatanPhase.AWAIT_ROLL, turn = 0, turnNumber = 1, setupIndex = 6)
+    }
+
+    private fun dice(total: Int): List<Int> = if (total <= 7) listOf(1, total - 1) else listOf(total - 6, 6)
+
+    /** A cloth game with seat 0 and seat 1 both settled beside the first village, the robber elsewhere. */
+    private fun clothGame(): Pair<CatanState, Int> {
+        val s = start(SeaScenario.CLOTH_FOR_CATAN)
+        val village = s.terrains.indexOf(Terrain.VILLAGE)
+        val corners = s.topo.HEX_CORNERS[village]
+        val elsewhere = s.terrains.indices.first { s.topo.land[it] && it != village && s.terrains[it] != Terrain.VILLAGE }
+        val staged = s.copy(
+            robber = elsewhere,
+            buildings = s.buildings.toMutableList().also {
+                it[corners[0]] = CatanBuilding(BuildingType.SETTLEMENT, 0)
+                it[corners[3]] = CatanBuilding(BuildingType.CITY, 1)
+            },
+        )
+        return staged to village
+    }
+
+    private fun roll(s: CatanState, number: Int) = CatanRules.applyMove(s, s.turn, RollDice(dice(number)))
+
+    @Test
+    fun `a village pays one cloth to every settlement beside it, a city no more`() {
+        val (s, village) = clothGame()
+        val number = s.numbers[village]
+        assertTrue(number in 2..12 && number != 7)
+        val after = roll(s, number)
+        assertEquals(listOf(1, 1, 0), after.sea!!.cloth)
+        assertEquals(SeaBoards.VILLAGE_CLOTH - 2, after.sea!!.villageCloth[village])
+        assertTrue(after.log.any { "village" in it && "cloth" in it })
+    }
+
+    @Test
+    fun `an empty village pays nothing and the last token goes to the seat nearest the roller`() {
+        val (s, village) = clothGame()
+        val low = s.copy(sea = s.sea!!.copy(villageCloth = s.sea!!.villageCloth.toMutableList().also { it[village] = 1 }))
+        val after = roll(low.copy(turn = 1), low.numbers[village])
+        assertEquals(listOf(0, 1, 0), after.sea!!.cloth)
+        assertEquals(0, after.sea!!.villageCloth[village])
+        val again = roll(after.copy(phase = CatanPhase.AWAIT_ROLL), after.numbers[village])
+        assertEquals(listOf(0, 1, 0), again.sea!!.cloth)
+    }
+
+    @Test
+    fun `the robber on a village stops it`() {
+        val (s, village) = clothGame()
+        val after = roll(s.copy(robber = village), s.numbers[village])
+        assertEquals(listOf(0, 0, 0), after.sea!!.cloth)
+    }
+
+    @Test
+    fun `every two cloth are a victory point, and the whole thing survives the wire format`() {
+        val (s, _) = clothGame()
+        val rich = s.copy(sea = s.sea!!.copy(cloth = listOf(5, 1, 0)))
+        assertEquals(CatanRules.publicVictoryPoints(s)[0] + 2, CatanRules.publicVictoryPoints(rich)[0])
+        assertEquals(CatanRules.publicVictoryPoints(s)[1], CatanRules.publicVictoryPoints(rich)[1])
+        assertEquals(rich, CatanRules.decodeState(CatanRules.encodeState(rich)))
+    }
+
+    @Test
+    fun `villages pay cloth with Cities and Knights too`() {
+        val options = CatanOptions(
+            playerCount = 3,
+            pointsToWin = 14,
+            expansions = setOf(CatanExpansion.SEAFARERS, CatanExpansion.CITIES_AND_KNIGHTS),
+            scenario = SeaScenario.CLOTH_FOR_CATAN,
+        )
+        val config = TableConfig(
+            gameId = GameCatalog.CATAN,
+            seats = (0 until 3).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
+            optionsJson = json.encodeToString(options),
+            seed = 5L,
+        )
+        val s = CatanRules.initialState(config)
+            .copy(phase = CatanPhase.AWAIT_ROLL, turn = 0, turnNumber = 1, setupIndex = 6)
+        val village = s.terrains.indexOf(Terrain.VILLAGE)
+        val elsewhere = s.terrains.indices.first { s.topo.land[it] && it != village && s.terrains[it] != Terrain.VILLAGE }
+        val staged = s.copy(
+            robber = elsewhere,
+            buildings = s.buildings.toMutableList().also {
+                it[s.topo.HEX_CORNERS[village][0]] = CatanBuilding(BuildingType.SETTLEMENT, 2)
+            },
+        )
+        val after = roll(staged, staged.numbers[village])
+        assertEquals(1, after.sea!!.cloth[2])
+    }
+
+    // ---- The Forgotten Tribe ----
+
+    /** A tribe game, seat 0 with a road reaching a settlement site beside [chipHex], and plenty of cards. */
+    private fun tribeGame(chip: TribeChip): Triple<CatanState, Int, Int> {
+        val s = start(SeaScenario.FORGOTTEN_TRIBE)
+        val hex = s.sea!!.chips.indexOfFirst { it != TribeChip.NONE }
+        val chips = s.sea!!.chips.toMutableList().also { it[hex] = chip }
+        val topo = s.topo
+        val vertex = topo.HEX_CORNERS[hex].first { v -> topo.VERTEX_NEIGHBORS[v].all { s.buildings[it] == null } }
+        val edge = topo.VERTEX_EDGES[vertex].first { topo.edgeLand[it] }
+        val staged = s.copy(
+            phase = CatanPhase.PLAYING,
+            roads = s.roads.toMutableList().also { it[edge] = 0 },
+            resources = List(3) { Resource.entries.associateWith { 4 } },
+            sea = s.sea!!.copy(chips = chips),
+        )
+        return Triple(staged, hex, vertex)
+    }
+
+    @Test
+    fun `the first settler beside a point chip takes the point`() {
+        val (s, hex, vertex) = tribeGame(TribeChip.POINT)
+        val after = CatanRules.applyMove(s, 0, BuildSettlement(vertex))
+        assertEquals(1, after.sea!!.chipPoints[0])
+        assertEquals(TribeChip.NONE, after.sea!!.chips[hex])
+        assertEquals(CatanRules.publicVictoryPoints(s)[0] + 1 + 1 + 2, CatanRules.publicVictoryPoints(after)[0])
+    }
+
+    @Test
+    fun `a harbour chip trades three to one anywhere`() {
+        val (s, _, vertex) = tribeGame(TribeChip.HARBOUR)
+        assertEquals(4, CatanRules.bestPortRatio(s, 0, Resource.WOOL))
+        val after = CatanRules.applyMove(s, 0, BuildSettlement(vertex))
+        assertEquals(listOf(0), after.sea!!.harbourSeats)
+        assertEquals(3, CatanRules.bestPortRatio(after, 0, Resource.WOOL))
+        assertEquals(4, CatanRules.bestPortRatio(after, 1, Resource.WOOL))
+        assertTrue(CatanRules.legalMoves(after, 0).any { it is MaritimeTrade })
+    }
+
+    @Test
+    fun `a gold chip asks for two resources of the settler's choice`() {
+        val (s, _, vertex) = tribeGame(TribeChip.GOLD)
+        val after = CatanRules.applyMove(s, 0, BuildSettlement(vertex))
+        assertEquals(CatanPhase.GOLD, after.phase)
+        assertEquals(listOf(GoldOwed(0, 2)), after.sea!!.gold)
+        val done = CatanRules.applyMove(after, 0, CatanRules.legalMoves(after, 0).first())
+        assertEquals(CatanPhase.PLAYING, done.phase)
+    }
+}

app/src/test/java/org/prolibertate/games/game/catan/CatanSeaScenariosTest.kt

@@ -0,0 +1,245 @@
+package org.prolibertate.games.game.catan
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+/** What every Seafarers map owes the engine, and the shape of each one. */
+class CatanSeaScenariosTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun options(scenario: SeaScenario, players: Int = 3) = CatanOptions(
+        playerCount = players,
+        pointsToWin = 12,
+        expansions = setOf(CatanExpansion.SEAFARERS),
+        scenario = scenario,
+    )
+
+    private fun config(options: CatanOptions, seed: Long) = TableConfig(
+        gameId = GameCatalog.CATAN,
+        seats = (0 until options.playerCount).map {
+            PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it)
+        },
+        optionsJson = json.encodeToString(options),
+        seed = seed,
+    )
+
+    private fun sizes(scenario: SeaScenario): List<Int> {
+        val topo = SeaBoards.topology(scenario)
+        return (0 until topo.islandCount).map { i -> topo.islandOf.count { it == i } }.sorted()
+    }
+
+    @Test
+    fun `each map has the islands it is named for`() {
+        assertEquals(listOf(2, 3, 3, 21), sizes(SeaScenario.NEW_SHORES))
+        assertEquals(listOf(1, 1, 6, 6, 6, 6), sizes(SeaScenario.FOUR_ISLANDS))
+        assertEquals(listOf(1, 1, 1, 2, 25), sizes(SeaScenario.THROUGH_THE_DESERT))
+        assertEquals(listOf(2, 13, 14), sizes(SeaScenario.FOG_ISLANDS))
+        assertEquals(listOf(2, 3, 6, 17), sizes(SeaScenario.CLOTH_FOR_CATAN))
+        assertEquals(listOf(2, 3, 5, 17), sizes(SeaScenario.FORGOTTEN_TRIBE))
+    }
+
+    @Test
+    fun `every map deals numbers, harbours and a pirate at sea, with the reds apart`() {
+        for (scenario in SeaScenario.entries) {
+            repeat(5) { i ->
+                val s = CatanRules.initialState(config(options(scenario), 300L + i))
+                val topo = s.topo
+                val deserts = s.terrains.count { it == Terrain.DESERT }
+                for (h in 0 until topo.HEX_COUNT) {
+                    val land = s.terrains[h] != Terrain.SEA
+                    assertEquals("$scenario hex $h", topo.land[h], land)
+                    val unnumbered = s.terrains[h] == Terrain.DESERT || s.terrains[h] == Terrain.FOG
+                    assertEquals("$scenario hex $h", land && !unnumbered, s.numbers[h] != 0)
+                }
+                val deserted = scenario != SeaScenario.FOUR_ISLANDS && scenario != SeaScenario.CLOTH_FOR_CATAN &&
+                    scenario != SeaScenario.FORGOTTEN_TRIBE
+                assertTrue("$scenario has no desert", deserts > 0 || !deserted)
+                // Under fog every hex is face down with no number; the tiles are in the pile.
+                val fog = s.terrains.indices.filter { s.terrains[it] == Terrain.FOG }
+                assertEquals(fog.size, s.sea!!.fogDeck.size)
+                fog.forEach { assertEquals(0, s.numbers[it]) }
+                assertEquals(Terrain.SEA, s.terrains[s.sea!!.pirate])
+                assertEquals("$scenario harbours", 9, s.ports.size)
+                val reds = (0 until topo.HEX_COUNT).filter { s.numbers[it] == 6 || s.numbers[it] == 8 }
+                for (a in reds) for (b in reds) if (a < b) assertFalse("$scenario reds touch", topo.hexesAdjacent(a, b))
+                assertEquals(scenario, s.sea!!.scenario)
+            }
+        }
+    }
+
+    @Test
+    fun `four islands start on any main island and the islets earn the bonus`() {
+        val s = CatanRules.initialState(config(options(SeaScenario.FOUR_ISLANDS), 5L))
+        val sea = s.sea!!
+        assertEquals(4, sea.starts.size)
+        val moves = CatanRules.legalMoves(s, s.firstSeat).filterIsInstance<SetupPlace>()
+        assertEquals(sea.starts.toSet(), moves.map { s.topo.vertexIsland[it.vertex] }.toSet())
+        for (island in 0 until s.topo.islandCount) assertEquals(island in sea.starts, sea.isStart(island))
+        // A settlement on a starting island scores no first-landing bonus.
+        val onMain = (0 until s.topo.VERTEX_COUNT).first { s.topo.vertexIsland[it] == sea.starts.first() }
+        assertEquals(s, SeaRules.claimIsland(s, 0, onMain))
+        val islet = (0 until s.topo.VERTEX_COUNT).first { s.topo.vertexIsland[it] >= 0 && s.topo.vertexIsland[it] !in sea.starts }
+        assertEquals(0, SeaRules.bonusPoints(s, 0))
+        assertEquals(0, SeaRules.bonusPoints(SeaRules.claimIsland(s, 0, onMain), 0))
+        assertEquals(SeaRules.ISLAND_BONUS, SeaRules.bonusPoints(SeaRules.claimIsland(s, 0, islet), 0))
+    }
+
+    @Test
+    fun `through the desert starts everyone on the one big island`() {
+        val s = CatanRules.initialState(config(options(SeaScenario.THROUGH_THE_DESERT), 5L))
+        assertEquals(listOf(s.sea!!.home), s.sea!!.starts)
+        assertEquals(25, s.topo.islandOf.count { it == s.sea!!.home })
+        assertTrue(s.terrains.count { it == Terrain.DESERT } >= 5)
+    }
+
+    @Test
+    fun `a save from before there were several starts still starts on the home island`() {
+        val s = CatanRules.initialState(config(options(SeaScenario.NEW_SHORES), 5L))
+        val old = s.copy(sea = s.sea!!.copy(starts = emptyList()))
+        assertTrue(old.sea!!.isStart(old.sea!!.home))
+        val moves = CatanRules.legalMoves(old, old.firstSeat).filterIsInstance<SetupPlace>()
+        assertTrue(moves.all { old.topo.vertexIsland[it.vertex] == old.sea!!.home })
+    }
+
+    private fun fogGame(seed: Long = 5L) = CatanRules.initialState(config(options(SeaScenario.FOG_ISLANDS), seed)).let {
+        it.copy(phase = CatanPhase.PLAYING, turn = 0, turnNumber = 1, setupIndex = 6)
+    }
+
+    /** A town site on the home island, ships already laid toward the fog, and the one edge that will reach it. */
+    private data class FogRoute(val town: Int, val laid: List<Int>, val last: Int)
+
+    private fun CatanState.fogRoute(): FogRoute {
+        val topo = topo
+        fun touchesFog(v: Int) = topo.VERTEX_HEXES[v].any { terrains[it] == Terrain.FOG }
+        val seen = mutableSetOf<Int>()
+        for (start in 0 until topo.VERTEX_COUNT) {
+            if (topo.vertexIsland[start] != sea!!.home || touchesFog(start)) continue
+            if (topo.VERTEX_EDGES[start].none { topo.edgeSea[it] && !topo.edgeLand[it] }) continue
+            val queue = ArrayDeque<Pair<Int, List<Int>>>().apply { add(start to emptyList()) }
+            seen.clear()
+            while (queue.isNotEmpty()) {
+                val (v, path) = queue.removeFirst()
+                if (!seen.add(v)) continue
+                for (e in topo.VERTEX_EDGES[v]) {
+                    if (!topo.edgeSea[e] || topo.edgeLand[e]) continue
+                    val far = topo.otherEnd(e, v)
+                    if (touchesFog(far)) return FogRoute(start, path, e)
+                    if (path.size < 6) queue.add(far to path + e)
+                }
+            }
+        }
+        error("no ship route from home reaches the fog")
+    }
+
+    /** [fogRoute] laid on the board: the town and all but the last ship. */
+    private fun CatanState.onTheShore(route: FogRoute): CatanState = copy(
+        buildings = buildings.toMutableList().also { it[route.town] = CatanBuilding(BuildingType.SETTLEMENT, 0) },
+        sea = sea!!.copy(ships = sea!!.ships.toMutableList().also { l -> route.laid.forEach { l[it] = 0 } }),
+        resources = List(3) { Resource.entries.associateWith { 3 } },
+    )
+
+    @Test
+    fun `fog is hidden at the start, never a place to begin, and keeps the robber off`() {
+        val s = CatanRules.initialState(config(options(SeaScenario.FOG_ISLANDS), 5L))
+        assertFalse(s.sea!!.isStart(s.topo.islandOf.indices.first { s.terrains[it] == Terrain.FOG }.let { s.topo.islandOf[it] }))
+        val moves = CatanRules.legalMoves(s, s.firstSeat).filterIsInstance<SetupPlace>()
+        assertTrue(moves.all { m -> s.topo.VERTEX_HEXES[m.vertex].none { s.terrains[it] == Terrain.FOG } })
+        val robbing = fogGame().copy(phase = CatanPhase.ROBBER)
+        val targets = CatanRules.legalMoves(robbing, 0).filterIsInstance<MoveRobber>()
+        assertTrue(targets.isNotEmpty())
+        assertTrue(targets.none { robbing.terrains[robbing.topo.hexIndex.getValue(it.hex)] == Terrain.FOG })
+    }
+
+    @Test
+    fun `a ship that reaches the fog turns the hex over and the finder takes a card`() {
+        val base = fogGame()
+        val route = base.fogRoute()
+        val edge = route.last
+        val s = base.onTheShore(route)
+        val tile = s.sea!!.fogDeck.first()
+        val after = CatanRules.applyMove(s, 0, BuildShip(edge))
+        val found = s.topo.EDGE_VERTICES[edge].toList().flatMap { s.topo.VERTEX_HEXES[it] }
+            .filter { s.terrains[it] == Terrain.FOG }.distinct().sorted()
+        val hex = found.first()
+        assertEquals(tile.terrain, after.terrains[hex])
+        assertEquals(tile.number, after.numbers[hex])
+        assertEquals(s.sea!!.fogDeck.size - found.size, after.sea!!.fogDeck.size)
+        val produced = tile.terrain.produces
+        if (produced != null) assertEquals(s.resources[0].getValue(produced) - (if (produced in SeaRules.SHIP_COST) 1 else 0) + 1,
+            after.resources[0].getValue(produced) - (found.drop(1).count { after.terrains[it].produces == produced }))
+        if (tile.terrain == Terrain.GOLD) assertEquals(CatanPhase.GOLD, after.phase)
+        // The find is public: the log names it.
+        assertTrue(after.log.last { "uncovers" in it }.isNotBlank())
+    }
+
+    @Test
+    fun `a gold find during road building asks for the choice and then goes back to the free roads`() {
+        val base = fogGame()
+        val route = base.fogRoute()
+        val edge = route.last
+        val gold = FogTile(Terrain.GOLD, 6)
+        val shore = base.onTheShore(route)
+        val s = shore.copy(
+            phase = CatanPhase.FREE_ROADS,
+            pendingFreeRoads = 2,
+            sea = shore.sea!!.copy(fogDeck = List(shore.sea!!.fogDeck.size) { gold }),
+        )
+        val after = CatanRules.applyMove(s, 0, BuildShip(edge))
+        assertEquals(CatanPhase.GOLD, after.phase)
+        val pick = CatanRules.legalMoves(after, 0).filterIsInstance<PickGold>().first()
+        val resumed = CatanRules.applyMove(after, 0, pick)
+        assertEquals(CatanPhase.FREE_ROADS, resumed.phase)
+        assertEquals(1, resumed.pendingFreeRoads)
+    }
+
+    @Test
+    fun `other seats do not see the face-down tiles and the state survives its wire format`() {
+        val s = fogGame()
+        assertTrue(s.sea!!.fogDeck.isNotEmpty())
+        assertTrue(CatanRules.viewFor(s, 1).sea!!.fogDeck.isEmpty())
+        assertEquals(s, CatanRules.decodeState(CatanRules.encodeState(s)))
+    }
+
+    @Test
+    fun `engines finish a game on every map at three and four players`() {
+        var fogFound = 0
+        var clothPaid = 0
+        var chipsTaken = 0
+        for (scenario in SeaScenario.entries) {
+            for ((players, seed) in listOf(3 to 11L, 4 to 12L, 3 to 13L)) {
+                val opts = options(scenario, players)
+                val ai = CatanAi()
+                var state = CatanRules.initialState(config(opts, seed))
+                var moves = 0
+                while (!CatanRules.isFinished(state)) {
+                    assertTrue("$scenario seed $seed ran past the cap; log: ${state.log.takeLast(6)}", moves++ < 20_000)
+                    val seat = CatanRules.currentSeat(state) ?: error("$scenario seed $seed: nobody to move in ${state.phase}")
+                    val legal = CatanRules.legalMoves(state, seat)
+                    assertTrue("$scenario seed $seed: no legal move for $seat in ${state.phase}", legal.isNotEmpty())
+                    val move = ai.chooseMove(state, seat, legal)
+                    assertTrue("$scenario seed $seed: illegal $move", CatanRules.isLegalMove(state, seat, move))
+                    state = CatanRules.applyMove(state, seat, move)
+                }
+                assertEquals("$scenario seed $seed", CatanPhase.GAME_OVER, state.phase)
+                if (scenario == SeaScenario.FOG_ISLANDS) fogFound += 14 - state.sea!!.fogDeck.size
+                if (scenario == SeaScenario.CLOTH_FOR_CATAN) clothPaid += state.sea!!.cloth.sum()
+                if (scenario == SeaScenario.FORGOTTEN_TRIBE) {
+                    chipsTaken += 4 - state.sea!!.chips.count { it != TribeChip.NONE }
+                }
+                assertEquals(state, CatanRules.decodeState(CatanRules.encodeState(state)))
+            }
+        }
+        assertTrue("no engine ever uncovered a fog hex", fogFound > 0)
+        assertTrue("no village ever paid cloth", clothPaid > 0)
+        assertTrue("no tribe chip was ever taken", chipsTaken > 0)
+    }
+}

app/src/test/java/org/prolibertate/games/game/catan/CatanSeafarersTest.kt

@@ -17,7 +17,7 @@ class CatanSeafarersTest {
     private val json = Json { encodeDefaults = true }
 
     private fun options(players: Int = 3) =
-        CatanOptions(playerCount = players, pointsToWin = 12, ruleSet = CatanRuleSet.SEAFARERS)
+        CatanOptions(playerCount = players, pointsToWin = 12, expansions = setOf(CatanExpansion.SEAFARERS))
 
     private fun config(options: CatanOptions, seed: Long) = TableConfig(
         gameId = GameCatalog.CATAN,
@@ -96,7 +96,7 @@ class CatanSeafarersTest {
     @Test
     fun `setup places both settlements on the home island, with roads rather than ships`() {
         val s = start()
-        val moves = CatanRules.legalMoves(s, 0).filterIsInstance<SetupPlace>()
+        val moves = CatanRules.legalMoves(s, s.firstSeat).filterIsInstance<SetupPlace>()
         assertTrue(moves.isNotEmpty())
         assertTrue(moves.all { s.topo.vertexIsland[it.vertex] == s.sea!!.home })
         assertTrue(moves.all { s.topo.edgeLand[it.edge] })

app/src/test/java/org/prolibertate/games/net/SaveRoundTripAllGamesTest.kt

@@ -171,7 +171,7 @@ class SaveRoundTripAllGamesTest {
         GameCatalog.CATAN,
         CatanRules,
         CatanAi(),
-        opts(CatanOptions(3, 13, org.prolibertate.games.game.catan.CatanRuleSet.CITIES_AND_KNIGHTS)),
+        opts(CatanOptions(3, 13, setOf(org.prolibertate.games.game.catan.CatanExpansion.CITIES_AND_KNIGHTS))),
         steps = 600,
     )
 }

app/src/test/java/org/prolibertate/games/ui/game/catan/CatanCkInteractionTest.kt

@@ -21,7 +21,7 @@ import org.prolibertate.games.game.catan.CatanBoard
 import org.prolibertate.games.game.catan.CatanMove
 import org.prolibertate.games.game.catan.CatanOptions
 import org.prolibertate.games.game.catan.CatanPhase
-import org.prolibertate.games.game.catan.CatanRuleSet
+import org.prolibertate.games.game.catan.CatanExpansion
 import org.prolibertate.games.game.catan.CatanRules
 import org.prolibertate.games.game.catan.CatanState
 import org.prolibertate.games.game.catan.ChaseRobber
@@ -69,7 +69,7 @@ class CatanCkInteractionTest {
         gameId = GameCatalog.CATAN,
         seats = (0 until players).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
         optionsJson = json.encodeToString(
-            CatanOptions(players, pointsToWin = 13, ruleSet = CatanRuleSet.CITIES_AND_KNIGHTS),
+            CatanOptions(players, pointsToWin = 13, expansions = setOf(CatanExpansion.CITIES_AND_KNIGHTS)),
         ),
         seed = seed,
     )

app/src/test/java/org/prolibertate/games/ui/game/catan/CatanCkTextTest.kt

@@ -8,7 +8,7 @@ import org.junit.Test
 import org.prolibertate.games.game.GameCatalog
 import org.prolibertate.games.game.catan.CatanAi
 import org.prolibertate.games.game.catan.CatanOptions
-import org.prolibertate.games.game.catan.CatanRuleSet
+import org.prolibertate.games.game.catan.CatanExpansion
 import org.prolibertate.games.game.catan.CatanRules
 import org.prolibertate.games.game.catan.ProgressType
 import org.prolibertate.games.game.engine.PlayerKind
@@ -16,7 +16,7 @@ import org.prolibertate.games.game.engine.PlayerSlot
 import org.prolibertate.games.game.engine.TableConfig
 import org.prolibertate.games.ui.catanDefaultPoints
 import org.prolibertate.games.ui.catanPointsChoices
-import org.prolibertate.games.ui.catanSwitchRules
+import org.prolibertate.games.ui.catanToggleExpansion
 
 class CatanCkTextTest {
 
@@ -28,7 +28,7 @@ class CatanCkTextTest {
             gameId = GameCatalog.CATAN,
             seats = (0 until 3).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
             optionsJson = json.encodeToString(
-                CatanOptions(3, 13, CatanRuleSet.CITIES_AND_KNIGHTS),
+                CatanOptions(3, 13, setOf(CatanExpansion.CITIES_AND_KNIGHTS)),
             ),
             seed = 31L,
         )
@@ -56,20 +56,27 @@ class CatanCkTextTest {
 
     @Test
     fun `the setup screen offers each rule set its own targets and switches sensibly`() {
-        assertEquals(listOf(5, 8, 10, 12), catanPointsChoices(CatanRuleSet.BASE))
-        assertEquals(listOf(8, 10, 13, 15), catanPointsChoices(CatanRuleSet.CITIES_AND_KNIGHTS))
-        assertEquals(10, catanDefaultPoints(CatanRuleSet.BASE))
-        assertEquals(13, catanDefaultPoints(CatanRuleSet.CITIES_AND_KNIGHTS))
+        assertEquals(listOf(5, 8, 10, 12), catanPointsChoices(emptySet()))
+        assertEquals(listOf(8, 10, 13, 15), catanPointsChoices(setOf(CatanExpansion.CITIES_AND_KNIGHTS)))
+        assertEquals(10, catanDefaultPoints(emptySet()))
+        assertEquals(13, catanDefaultPoints(setOf(CatanExpansion.CITIES_AND_KNIGHTS)))
 
         val base = CatanOptions()
-        val ck = catanSwitchRules(base, CatanRuleSet.CITIES_AND_KNIGHTS)
-        assertEquals(CatanRuleSet.CITIES_AND_KNIGHTS, ck.ruleSet)
+        val ck = catanToggleExpansion(base, CatanExpansion.CITIES_AND_KNIGHTS, true)
+        assertEquals(setOf(CatanExpansion.CITIES_AND_KNIGHTS), ck.expansions)
         assertEquals("the published target for the new rules", 13, ck.pointsToWin)
-        assertEquals(10, catanSwitchRules(ck, CatanRuleSet.BASE).pointsToWin)
+        assertEquals(10, catanToggleExpansion(ck, CatanExpansion.CITIES_AND_KNIGHTS, false).pointsToWin)
 
         // A short game picked on purpose is kept when both menus have it.
-        val short = catanSwitchRules(base.copy(pointsToWin = 8), CatanRuleSet.CITIES_AND_KNIGHTS)
+        val short = catanToggleExpansion(base.copy(pointsToWin = 8), CatanExpansion.CITIES_AND_KNIGHTS, true)
         assertEquals(8, short.pointsToWin)
         assertEquals(3, ck.playerCount)
+
+        // Expansions stack: both on has its own menu, and turning one off leaves the other.
+        val both = catanToggleExpansion(ck, CatanExpansion.SEAFARERS, true)
+        assertEquals(setOf(CatanExpansion.CITIES_AND_KNIGHTS, CatanExpansion.SEAFARERS), both.expansions)
+        assertEquals(listOf(10, 12, 14, 16), catanPointsChoices(both.expansions))
+        assertEquals(14, both.pointsToWin)
+        assertEquals(setOf(CatanExpansion.SEAFARERS), catanToggleExpansion(both, CatanExpansion.CITIES_AND_KNIGHTS, false).expansions)
     }
 }

app/src/test/java/org/prolibertate/games/ui/game/catan/CatanFixtures.kt

@@ -28,7 +28,8 @@ internal object CatanFixtures {
 
     /** A fresh table, on the first setup placement. */
     fun start(players: Int = 3, seed: Long = 7L): CatanState =
-        CatanRules.initialState(config(players, seed))
+        // These tests are about the screen, not who starts: pin seat 0 first.
+        CatanRules.initialState(config(players, seed)).let { it.copy(firstSeat = 0, turn = 0) }
 
     /** A mid-game state on [turn]'s turn, then adjusted by [adjust]. */
     fun playing(

app/src/test/java/org/prolibertate/games/ui/game/catan/CatanSeafarersInteractionTest.kt

@@ -12,7 +12,7 @@ import org.prolibertate.games.game.catan.CatanAi
 import org.prolibertate.games.game.catan.CatanBuilding
 import org.prolibertate.games.game.catan.CatanOptions
 import org.prolibertate.games.game.catan.CatanPhase
-import org.prolibertate.games.game.catan.CatanRuleSet
+import org.prolibertate.games.game.catan.CatanExpansion
 import org.prolibertate.games.game.catan.CatanRules
 import org.prolibertate.games.game.catan.CatanState
 import org.prolibertate.games.game.catan.MovePirate
@@ -29,7 +29,7 @@ import org.prolibertate.games.game.engine.TableConfig
 class CatanSeafarersInteractionTest {
 
     private fun fresh(): CatanState {
-        val options = CatanOptions(playerCount = 3, pointsToWin = 12, ruleSet = CatanRuleSet.SEAFARERS)
+        val options = CatanOptions(playerCount = 3, pointsToWin = 12, expansions = setOf(CatanExpansion.SEAFARERS))
         return CatanRules.initialState(
             TableConfig(
                 gameId = GameCatalog.CATAN,

docs/RULES-catan-ck.md

@@ -220,3 +220,10 @@ game in `CatanCkSelfPlayTest` ends in a win at thirteen points.
 - No animation for the event die, the barbarian landing or a knight's move.
 - The Commercial Harbor offers a single resource type (see above).
 - The AI is not a strong opponent and makes no claim to be.
+
+## On a Seafarers map
+
+Cities & Knights can be played on a Seafarers map; the rules for how the two meet are in
+[RULES-catan-seafarers.md](RULES-catan-seafarers.md#with-cities--knights). The code reads the board from
+`state.topo` throughout, so nothing here assumes the 19-hex island.
+

docs/RULES-catan-seafarers.md

@@ -1,20 +1,38 @@
 # Katan: Seafarers
 
-The Seafarers rule set is chosen at setup next to *Base game* and *Cities & Knights*. It is the base
+Seafarers is an expansion switched on at setup (`CatanOptions.expansions`; the old single `ruleSet` in saves is still read) and its map is chosen beside it (`CatanOptions.scenario`). It is the base
 game ([RULES-catan.md](RULES-catan.md)) with a sea, ships, a pirate, gold fields and islands to
 settle. Code: `game/catan/CatanSeaRules.kt` (the additions), `CatanSeaBoard.kt` (the map),
 `CatanBoard.kt` (`Topology`, the geometry shared by every map), state behind `CatanState.sea`
-(null in the other rule sets). It cannot be combined with Cities & Knights.
+(null in the other rule sets). It can be combined with Cities & Knights; see *With Cities & Knights* below.
 
 Where the published rules leave room, or where this game differs, it says so below.
 
-## The map
+## The maps
 
-One map, *Heading for New Shores*: a large **home island** (21 hexes, one desert) and three small
-islands (3, 3 and 2 hexes) across the water, inside a ring of sea. Which land hexes are gold, which
-are the desert and where the sea lies is fixed; the **resources on the other hexes, the number tokens
+Each map is a fixed arrangement of land and sea; the **resources on the plain hexes, the number tokens
 and the nine harbours are shuffled** for each game. The red numbers (6, 8) are never on neighbouring
 hexes. Players take three or four seats; the default target is **12 points** (menu: 8, 10, 12, 14).
+Pick the map at setup; each scenario names where the starting settlements may go (`SeaStart`).
+
+* **Heading for New Shores** (default). A large home island (21 hexes, one desert) and three small islands (3, 3
+  and 2 hexes) across the water, with gold fields on two of the small ones. Start on the home island.
+* **Four Islands.** Four equal islands (six hexes each) and two one-hex gold islets between them. Each player
+  may start on **any** of the four main islands, so a table can spread out or crowd one; the islets are the
+  prize for the first ship to arrive.
+* **Through the Desert.** One 25-hex island cut across by a broad desert (seven hexes that pay nothing and
+  hold the robber), with three islets and gold to sail to. Everyone starts on the island. The desert is
+  land, so a road can cross it, but nothing beside it pays, which is what makes the far side a race.
+
+* **The Fog Islands.** A 13-hex home island (one desert), a two-hex islet and a 14-hex bank of fog.
+  See *Fog* below.
+
+* **Cloth for Catan.** A 17-hex main island, an eastern isle, two islets, and four **villages** on the coast.
+  See *Cloth* below.
+* **The Forgotten Tribe.** A 17-hex home island and three isles carrying four tribe chips. See *The Forgotten
+  Tribe* below.
+
+A *new island* for the bonus is any island that is not a starting island for that map.
 
 The geometry is the same lattice as the base island, generalised (`Topology`): a hex is land or sea,
 a crossing can hold a town if any hex touching it is land, an edge can hold a road if any hex touching
@@ -56,16 +74,77 @@ through an opponent's town and changes between road and ship only at a town of y
 
 Everything else (development cards, trading, harbours, Largest Army, the discard on a seven) is the base game.
 
+## Fog
+
+Fog hexes (`Terrain.FOG`) are land that is face down. Under them is a shuffled pile of tiles
+(`SeaState.fogDeck`): resources, with one gold field in every five, each with its number token. The
+pile is hidden from every seat but the host's, like the development deck.
+
+* **Finding.** When a road or ship is built (or a ship sails) and an end of it touches a fog hex, the hex is
+  turned over, taking the next tile and its number. Several hexes can be found by one piece.
+* **The find pays.** The finder takes one card of what lies there, supply permitting; a gold field lets the
+  finder choose any resource (the gold choice, resuming Road Building if that is what was under way).
+* **Until then** nothing produces there, nobody may start beside it, and the robber cannot go on it.
+* **Differences from the published scenario.** The fog here is always land: the physical tiles can turn out to
+  be sea, but the board's land and sea are fixed in the geometry, so a found hex never turns to water. Fog is
+  also on one bank rather than between several islands, and the number tokens are dealt with the tiles, so two
+  red numbers can end up side by side once found.
+
+## Cloth
+
+The published scenario puts cloth villages between the islands and pays cloth when a village's number is rolled.
+This implementation is the author's reading of that, not a transcription of the printed rules:
+
+* A **village** is a land hex with a number token and a stock of cloth (6). It produces no cards and nothing may
+  be built on it, but its corners can hold settlements like any other hex's.
+* When its number rolls, the village pays **one cloth token** to each settlement or city beside it (a city is
+  worth no more than a settlement here), until the stock is gone. If the stock is short, the seats nearest the
+  roller, in turn order, take what is left. The robber on a village stops it; the pirate does not.
+* **Two cloth are a victory point** (an odd token is worth nothing alone). Tokens are scored, not spent, and not
+  tradeable.
+* Works with Cities & Knights: the village pays after the dice, before the aqueduct and gold.
+
+## The Forgotten Tribe
+
+Also the author's reading. A chip lies face up on four hexes of the small isles (the hexes are marked on the
+board). The chips are dealt at the start of the game, one of each kind in turn:
+
+* **The first settlement** built on a crossing beside a chip hex takes that chip; it is gone for everyone else.
+  (The setup settlements are never beside one, since the home island is the only start.)
+* A **point** chip is one victory point. A **harbour** chip lets that seat trade 3:1 at the bank, wherever it is.
+  A **gold** chip pays two resources of the settler's choice, taken at once like gold.
+* The chips come on top of the island bonus for being first to a new island.
+
+## With Cities & Knights
+
+Switching both expansions on plays [Cities & Knights](RULES-catan-ck.md) on any Seafarers map
+(`CatanState.ck` and `CatanState.sea` both set; the target menu is 10, 12, 14 or 16, default 14).
+Where the two meet, this game decides as follows:
+
+* **Ships** cost 1 lumber and 1 wool as before and are built and sailed in a turn like a road, including
+  with the Road Building progress card (roads and ships, as in Seafarers).
+* **Knights** stand on land crossings at the end of one of your roads *or ships*, and walk along that same
+  network. A crossing that touches only sea is never a knight post.
+* **The pirate** sleeps with the robber: only after the first barbarian attack does a seven let the player
+  move the robber (to land) *or* the pirate (to sea). The pirate robs one good, resource or commodity, from a
+  seat with a ship beside it. The bishop moves the robber only.
+* **Gold** pays after the roll and before the aqueduct and any other chore: a settlement beside it chooses one
+  resource, a city two. (A city on gold takes two resources, not a resource and a commodity.)
+* **Scoring.** First-landing bonus points are added to a seat's points like any other; the barbarians count
+  cities wherever they stand, island or not.
+* **Merchant** goes only on a land hex; **Fog** works as in Seafarers (a find pays a resource card).
+
 ## Not included
 
 The physical expansion has more scenarios and the Catan Universe app adds more still. These are **out of scope here**:
-fog islands, treasure islands, the oasis, the great canal, the Explorers & Pirates and Cities & Knights combinations,
-the scenarios after the first, and trade ships. The `SeaScenario` enum and `SeaBoards` are built so a second map
-is a new text map and a new enum entry.
+treasure islands, the oasis, the great canal, the Explorers & Pirates combination,
+the scenarios that need new rules (wonders, pirate islands) and trade ships.
+A map-only scenario is a new text map and a new `SeaScenario` entry.
 
 ## How the AI plays it
 
 It settles first and sails second. A ship is built when a settlement spot reachable by sea (up to five steps from its
 open end) is worth having, with a bonus for an island nobody has landed on, and ahead of a development card when that
-bonus is in play. It chooses the resource it values most from gold, always moves the robber (never the pirate) and does
+bonus is in play. A spot beside a village that still has cloth, or beside a tribe chip nobody has taken, is
+worth more (`CatanAi.scenarioLure`). It chooses the resource it values most from gold, always moves the robber (never the pirate) and does
 not sail ships it has already launched. See `CatanAi.shipValue`.