Seafarers: Treasure Islands, Oases and the Great Canal (inferred rules)

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

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

@@ -279,6 +279,7 @@ class CatanAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) : GameAi<Ca
 
         // A raid on a fortress, or the next stage of a wonder, beats a card.
         legal.filterIsInstance<RaidFortress>().firstOrNull()?.let { return it }
+        legal.filterIsInstance<DigCanal>().firstOrNull()?.let { return it }
         legal.filterIsInstance<BuildWonder>().firstOrNull()?.let { return it }
 
         // Seafarers: a ship toward an island nobody has landed on is worth more than a card.
@@ -605,6 +606,8 @@ class CatanAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) : GameAi<Ca
             if (state.terrains[h] == Terrain.VILLAGE && sea.villageCloth.getOrElse(h) { 0 } > 0) {
                 lure += CatanBoard.numberOdds(state.numbers[h]) / 36.0 * CLOTH_WORTH
             }
+            // An unfinished canal tile is a place to dig: points now, grain land later.
+            if (sea.canalNumbers.getOrElse(h) { 0 } != 0 && state.terrains[h] == Terrain.DESERT) lure += CANAL_LURE
             if (sea.chips.getOrNull(h).let { it != null && it != TribeChip.NONE }) lure += CHIP_LURE
         }
         return lure
@@ -705,5 +708,6 @@ class CatanAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) : GameAi<Ca
         const val FORT_LURE = 1.2
         const val CLOTH_WORTH = 2.5
         const val CHIP_LURE = 0.5
+        const val CANAL_LURE = 0.6
     }
 }

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

@@ -215,6 +215,7 @@ internal class CatanCkAi(
         }
 
         legal.filterIsInstance<RaidFortress>().firstOrNull()?.let { return it }
+        legal.filterIsInstance<DigCanal>().firstOrNull()?.let { return it }
         legal.filterIsInstance<BuildWonder>().firstOrNull()?.let { return it }
 
         // Seafarers: a ship toward land nobody has settled is worth more than a card.

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

@@ -507,8 +507,34 @@ data class SeaState(
     val raidPoints: List<Int> = emptyList(),
     /** Wonder stages each seat has built (Wonders of Catan), by seat; empty when the scenario has none. */
     val wonders: List<Int> = emptyList(),
+    /** The chest under each hex of fog, by hex (Treasure Islands, Oases); found when the hex is. Hidden from other views. */
+    val treasures: List<Treasure> = emptyList(),
+    /** Units dug so far into each canal tile, by hex (Great Canal); empty when the map has none. */
+    val canalUnits: List<Int> = emptyList(),
+    /** The number token waiting under each canal tile, by hex; it shows when the tile is finished. */
+    val canalNumbers: List<Int> = emptyList(),
+    /** Canal units each seat has dug; every two are a victory point. */
+    val canalDug: List<Int> = emptyList(),
 )
 
+/** What a treasure chest holds (Treasure Islands). */
+@Serializable
+enum class Treasure {
+    NONE,
+
+    /** One brick, one wool and one grain. */
+    BRICK_WOOL_GRAIN,
+
+    /** One resource of the finder's choice. */
+    CHOICE,
+
+    /** A development card (a resource of choice in Cities & Knights, which has none). */
+    DEV_CARD,
+
+    /** Two roads' worth of cards: two lumber and two brick. */
+    ROADS,
+}
+
 /** What the first settler beside a tribe hex takes (Forgotten Tribe). */
 @Serializable
 enum class TribeChip {
@@ -563,3 +589,8 @@ data class RaidFortress(val hex: HexCoord) : CatanMove
 @Serializable
 @SerialName("wonder")
 data object BuildWonder : CatanMove
+
+/** Dig one unit of the canal tile on [hex]: 1 brick and 1 ore, from a seat with a settlement or city beside it. */
+@Serializable
+@SerialName("dig")
+data class DigCanal(val hex: HexCoord) : CatanMove

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

@@ -125,6 +125,10 @@ object CatanRules : GameRules<CatanState, CatanMove> {
                     villageCloth = it.villageCloth,
                     chips = it.chips,
                     fortress = it.fortress,
+                    treasures = it.treasures,
+                    canalUnits = if (it.canalNumbers.isEmpty()) emptyList() else List(topo.HEX_COUNT) { 0 },
+                    canalNumbers = it.canalNumbers,
+                    canalDug = if (it.canalNumbers.isEmpty()) emptyList() else List(options.playerCount) { 0 },
                     wonders = if (scenario == SeaScenario.WONDERS_OF_CATAN) List(options.playerCount) { 0 } else emptyList(),
                 )
             },
@@ -475,6 +479,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             is MovePirate -> applyMovePirate(state, seat, move)
             is PickGold -> applyPickGold(state, seat, move)
             is RaidFortress -> SeaRules.applyRaid(state, seat, move)
+            is DigCanal -> SeaRules.applyDig(state, seat, move)
             BuildWonder -> SeaRules.applyWonder(state, seat)
             is BuildRoad -> applyBuildRoad(state, seat, move)
             is BuildSettlement -> applyBuildSettlement(state, seat, move)
@@ -1226,7 +1231,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         state.copy(
             // Hidden information stays with the holder and the host.
             devDeck = emptyList(),
-            sea = state.sea?.copy(fogDeck = emptyList()),
+            sea = state.sea?.copy(fogDeck = emptyList(), treasures = emptyList()),
             devHands = state.devHands.mapIndexed { index, hand ->
                 if (index == seat) hand else emptyList()
             },

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

@@ -24,6 +24,21 @@ enum class SeaScenario(val title: String, val blurb: String, val start: SeaStart
         "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.",
     ),
+    TREASURE_ISLANDS(
+        "The Treasure Islands",
+        "Chests lie hidden on the fog-covered isles beside a home island. Whoever uncovers one opens it: " +
+            "cards, a resource of choice, a development card or a road's worth of materials.",
+    ),
+    OASES(
+        "The Oases",
+        "An enormous desert, with fertile oases hidden inside it. Roads that reach an oasis uncover it " +
+            "and whatever treasure is buried there.",
+    ),
+    GREAT_CANAL(
+        "The Great Canal",
+        "A desert strip splits the island. Dig the canal tile by tile (a brick and an ore a unit) and each finished " +
+            "tile becomes grain land; every two units dug are a victory point.",
+    ),
     PIRATE_ISLANDS(
         "Pirate Islands",
         "Two isles are held by pirate fortresses. Sail ships beside one and raid it with ore, wool and grain; " +
@@ -136,6 +151,39 @@ object SeaBoards {
         "............",
     )
 
+    private val TREASURE_ISLANDS_MAP = listOf(
+        "............",
+        "..###..FF...",
+        "..####..FF..",
+        "..#####.....",
+        "..###...F...",
+        ".......FF...",
+        "..F.........",
+        "............",
+    )
+
+    private val OASES_MAP = listOf(
+        "............",
+        "..###DD###..",
+        "..#DDFDD#...",
+        "..#DDDFD#...",
+        "..#DFDDD#...",
+        "..###DD###..",
+        "............",
+    )
+
+    /** `C` is a canal tile: desert with a number hidden under it until it is dug out. */
+    private val GREAT_CANAL_MAP = listOf(
+        "............",
+        "..#####.....",
+        "..#####.....",
+        "..CCCCC.....",
+        "..#####.....",
+        "..#####.....",
+        "........$$..",
+        "............",
+    )
+
     /** `P` is a pirate fortress. */
     private val PIRATE_ISLANDS_MAP = listOf(
         "............",
@@ -164,6 +212,9 @@ object SeaBoards {
         SeaScenario.FOUR_ISLANDS -> FOUR_ISLANDS_MAP
         SeaScenario.THROUGH_THE_DESERT -> THROUGH_THE_DESERT_MAP
         SeaScenario.FOG_ISLANDS -> FOG_ISLANDS_MAP
+        SeaScenario.TREASURE_ISLANDS -> TREASURE_ISLANDS_MAP
+        SeaScenario.OASES -> OASES_MAP
+        SeaScenario.GREAT_CANAL -> GREAT_CANAL_MAP
         SeaScenario.PIRATE_ISLANDS -> PIRATE_ISLANDS_MAP
         SeaScenario.WONDERS_OF_CATAN -> WONDERS_OF_CATAN_MAP
         SeaScenario.CLOTH_FOR_CATAN -> CLOTH_FOR_CATAN_MAP
@@ -215,6 +266,10 @@ object SeaBoards {
         val villageCloth: List<Int> = emptyList(),
         /** Strength of the fortress on each hex, by hex; empty when the map has none. */
         val fortress: List<Int> = emptyList(),
+        /** The chest under each hex, by hex; empty when the map has none. */
+        val treasures: List<Treasure> = emptyList(),
+        /** The number under each canal tile, by hex; empty when the map has none. */
+        val canalNumbers: List<Int> = emptyList(),
     )
 
     /** An island of this many land hexes or more can be started on. */
@@ -226,6 +281,9 @@ object SeaBoards {
     /** Ships' raids a pirate fortress takes to fall. */
     const val FORTRESS_STRENGTH = 3
 
+    /** Chests dealt to the fog, at most. */
+    private const val CHESTS = 5
+
     private val RESOURCE_TILES = listOf(
         Terrain.FOREST, Terrain.PASTURE, Terrain.FIELDS, Terrain.HILLS, Terrain.MOUNTAINS,
     )
@@ -250,13 +308,14 @@ object SeaBoards {
                 '#', 't' -> pool[plain.indexOf(h)]
                 'V' -> Terrain.VILLAGE
                 'P' -> Terrain.FORTRESS
+                'C' -> Terrain.DESERT
                 '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 && terrains[it] != Terrain.FORTRESS }
+        val numbered = terrains.indices.filter { terrains[it] != Terrain.SEA && (terrains[it] != Terrain.DESERT && terrains[it] != Terrain.FORTRESS || kinds[it] == 'C') }
         check(numbered.size <= TOKENS.size) { "Not enough number tokens for ${numbered.size} hexes" }
         val tokens = TOKENS.take(numbered.size).shuffled(random)
         val numbers = IntArray(terrains.size)
@@ -294,7 +353,9 @@ object SeaBoards {
         val desert = terrains.indexOf(Terrain.DESERT).takeIf { it >= 0 }
             ?: numbered.first()
         // 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 fogged = (0 until topo.islandCount).filter { island ->
+            topo.islandOf.indices.filter { topo.islandOf[it] == island }.all { terrains[it] == Terrain.FOG }
+        }.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.
@@ -334,6 +395,24 @@ object SeaBoards {
             List(terrains.size) { h -> if (terrains[h] == Terrain.FORTRESS) FORTRESS_STRENGTH else 0 }
         }
 
-        return Generated(terrains, numbers.toList(), desert, pirate, ports, home, starts, fogDeck, chips, villages, fortress)
+        // Chests under the fog: the four rewards in turn, on hexes picked at random.
+        val chestKinds = listOf(Treasure.BRICK_WOOL_GRAIN, Treasure.CHOICE, Treasure.DEV_CARD, Treasure.ROADS)
+        val chestHexes = if (scenario == SeaScenario.TREASURE_ISLANDS || scenario == SeaScenario.OASES) {
+            fogHexes.shuffled(random).take(CHESTS)
+        } else {
+            emptyList()
+        }
+        val treasures = if (chestHexes.isEmpty()) {
+            emptyList()
+        } else {
+            List(terrains.size) { h -> chestHexes.indexOf(h).let { if (it < 0) Treasure.NONE else chestKinds[it % chestKinds.size] } }
+        }
+
+        // Canal tiles keep their number under the tile until it is dug out.
+        val canalHexes = kinds.indices.filter { kinds[it] == 'C' }
+        val canalNumbers = if (canalHexes.isEmpty()) emptyList() else List(terrains.size) { h -> if (h in canalHexes) numbers[h] else 0 }
+        canalHexes.forEach { numbers[it] = 0 }
+
+        return Generated(terrains, numbers.toList(), desert, pirate, ports, home, starts, fogDeck, chips, villages, fortress, treasures, canalNumbers)
     }
 }

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

@@ -182,11 +182,55 @@ internal object SeaRules {
             } else if (tile.terrain == Terrain.GOLD) {
                 owed += GoldOwed(seat, 1)
             }
+            val chest = s.sea!!.treasures.getOrNull(hex) ?: Treasure.NONE
+            if (chest != Treasure.NONE) {
+                val (opened, choose) = openChest(s, seat, chest)
+                s = opened
+                if (choose > 0) owed += GoldOwed(seat, choose)
+            }
         }
         if (owed.isEmpty()) return s
         return owe(s, seat, owed.sumOf { it.count })
     }
 
+    /**
+     * [seat] opens [chest]: the state after what it pays directly, and the number of cards of the seat's own
+     * choice still owed. Cards the bank cannot cover are simply not paid.
+     */
+    private fun openChest(state: CatanState, seat: Int, chest: Treasure): Pair<CatanState, Int> {
+        var s = state
+        fun pay(cards: Map<Resource, Int>) {
+            val real = cards.filter { (r, n) -> CatanRules.bankSupply(s, r) >= n }
+            if (real.isNotEmpty()) s = s.copy(resources = CatanRules.withCounts(s.resources, seat, real, 1))
+        }
+        var choose = 0
+        val said = when (chest) {
+            Treasure.BRICK_WOOL_GRAIN -> {
+                pay(mapOf(Resource.BRICK to 1, Resource.WOOL to 1, Resource.GRAIN to 1))
+                "a brick, a wool and a grain"
+            }
+            Treasure.ROADS -> {
+                pay(mapOf(Resource.LUMBER to 2, Resource.BRICK to 2))
+                "materials for two roads"
+            }
+            Treasure.DEV_CARD -> if (!s.isCk && s.devDeck.isNotEmpty()) {
+                val card = s.devDeck.first().copy(boughtTurn = s.turnNumber)
+                val hands = s.devHands.toMutableList().also { it[seat] = it[seat] + card }
+                s = s.copy(devDeck = s.devDeck.drop(1), devHands = hands, devHandCounts = hands.map { it.size })
+                "a development card"
+            } else {
+                choose = 1
+                "a resource of its choice"
+            }
+            else -> {
+                choose = 1
+                "a resource of its choice"
+            }
+        }
+        s = s.copy(log = s.log + "Seat $seat opens a treasure chest: $said.")
+        return s to choose
+    }
+
     /** 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!!
@@ -208,7 +252,51 @@ internal object SeaRules {
             (sea.raidPoints.getOrNull(seat) ?: 0) +
             (sea.wonders.getOrNull(seat) ?: 0) +
             clothOf(state, seat) / CLOTH_PER_POINT +
-            (sea.chipPoints.getOrNull(seat) ?: 0)
+            (sea.chipPoints.getOrNull(seat) ?: 0) +
+            (sea.canalDug.getOrNull(seat) ?: 0) / CANAL_UNITS_PER_POINT
+    }
+
+    // -----------------------------------------------------------------------
+    // The Great Canal
+    // -----------------------------------------------------------------------
+
+    val DIG_COST: Map<Resource, Int> = mapOf(Resource.BRICK to 1, Resource.ORE to 1)
+
+    /** Units that finish a canal tile. */
+    const val CANAL_TILE_UNITS = 3
+
+    /** Two units dug are a victory point. */
+    const val CANAL_UNITS_PER_POINT = 2
+
+    /** Tiles [seat] may dig a unit of: unfinished, with a settlement or city of the seat's on a corner. */
+    private fun digTargets(state: CatanState, seat: Int): List<Int> {
+        val sea = state.sea!!
+        if (sea.canalUnits.isEmpty()) return emptyList()
+        return sea.canalUnits.indices.filter { h ->
+            sea.canalNumbers[h] != 0 && sea.canalUnits[h] in 0 until CANAL_TILE_UNITS &&
+                state.terrains[h] == Terrain.DESERT &&
+                state.topo.HEX_CORNERS[h].any { state.buildings[it]?.owner == seat }
+        }
+    }
+
+    fun applyDig(state: CatanState, seat: Int, move: DigCanal): CatanState {
+        val sea = state.sea!!
+        val hex = state.topo.hexIndex.getValue(move.hex)
+        val units = sea.canalUnits[hex] + 1
+        val dug = sea.canalDug.toMutableList().also { it[seat] += 1 }
+        var s = state.copy(
+            resources = CatanRules.withCounts(state.resources, seat, DIG_COST, -1),
+            sea = sea.copy(canalUnits = sea.canalUnits.toMutableList().also { it[hex] = units }, canalDug = dug),
+            log = state.log + "Seat $seat digs the canal at (${move.hex.q},${move.hex.r}): $units of $CANAL_TILE_UNITS.",
+        )
+        if (units == CANAL_TILE_UNITS) {
+            s = s.copy(
+                terrains = s.terrains.toMutableList().also { it[hex] = Terrain.FIELDS },
+                numbers = s.numbers.toMutableList().also { it[hex] = sea.canalNumbers[hex] },
+                log = s.log + "The tile is dug out: it is fields now, with a ${sea.canalNumbers[hex]}.",
+            )
+        }
+        return CatanRules.checkWin(s)
     }
 
     // -----------------------------------------------------------------------
@@ -328,6 +416,9 @@ internal object SeaRules {
         if (CatanRules.affordable(state, seat, RAID_COST)) {
             raidTargets(state, seat).forEach { moves += RaidFortress(state.topo.HEXES[it]) }
         }
+        if (CatanRules.affordable(state, seat, DIG_COST)) {
+            digTargets(state, seat).forEach { moves += DigCanal(state.topo.HEXES[it]) }
+        }
         nextStage(state, seat)?.let { if (CatanRules.affordable(state, seat, it)) moves += BuildWonder }
         return moves
     }

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

@@ -33,6 +33,7 @@ import org.prolibertate.games.game.catan.CatanBoard
 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.SeaRules
 import org.prolibertate.games.game.catan.Terrain
 import org.prolibertate.games.game.catan.TribeChip
 
@@ -170,6 +171,8 @@ private fun DrawScope.drawHexes(
         val sea = state.sea
         val note = when {
             state.terrains[hex] == Terrain.VILLAGE && sea != null -> "${sea.villageCloth.getOrElse(hex) { 0 }} cloth"
+            sea != null && sea.canalNumbers.getOrElse(hex) { 0 } != 0 && state.terrains[hex] == Terrain.DESERT ->
+                "dug ${sea.canalUnits.getOrElse(hex) { 0 }}/${SeaRules.CANAL_TILE_UNITS}"
             state.terrains[hex] == Terrain.FORTRESS && sea != null -> "fort ${sea.fortress.getOrElse(hex) { 0 }}"
             else -> when (sea?.chips?.getOrNull(hex)) {
                 TribeChip.POINT -> "+1 VP"

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

@@ -174,6 +174,7 @@ object CatanHudGlyphs {
         BuildKind.KNIGHT -> "♞"
         BuildKind.SHIP -> "⛵"
         BuildKind.RAID -> "⚔"
+        BuildKind.DIG -> "⛏"
         BuildKind.WONDER -> "✦"
     }
 
@@ -185,6 +186,7 @@ object CatanHudGlyphs {
         BuildKind.KNIGHT -> CatanText.KNIGHT
         BuildKind.SHIP -> CatanText.SHIP
         BuildKind.RAID -> CatanText.RAID
+        BuildKind.DIG -> CatanText.DIG
         BuildKind.WONDER -> CatanText.WONDER
     }
 }

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

@@ -7,6 +7,7 @@ import org.prolibertate.games.game.catan.BuildCity
 import org.prolibertate.games.game.catan.BuildRoad
 import org.prolibertate.games.game.catan.BuildShip
 import org.prolibertate.games.game.catan.BuildWonder
+import org.prolibertate.games.game.catan.DigCanal
 import org.prolibertate.games.game.catan.MovePirate
 import org.prolibertate.games.game.catan.RaidFortress
 import org.prolibertate.games.game.catan.MoveShip
@@ -74,6 +75,9 @@ enum class BuildKind {
     /** Pirate Islands: raid a fortress; the target is the fortress hex. */
     RAID,
 
+    /** Great Canal: dig a canal tile; the target is the tile. */
+    DIG,
+
     /** Wonders of Catan: the next stage of the wonder, which needs no tap on the board. */
     WONDER;
 
@@ -88,10 +92,11 @@ enum class BuildKind {
             val sea = state.sea
             val extras = buildList {
                 if (sea != null && sea.fortress.isNotEmpty()) add(RAID)
+                if (sea != null && sea.canalUnits.isNotEmpty()) add(DIG)
                 if (sea != null && sea.wonders.isNotEmpty()) add(WONDER)
             }
             val usual = when {
-                state.isCk -> entries.filter { it != SHIP || state.isSea } - listOf(RAID, WONDER)
+                state.isCk -> entries.filter { it != SHIP || state.isSea } - listOf(RAID, DIG, WONDER)
                 state.isSea -> SEAFARERS
                 else -> BASE
             }
@@ -278,6 +283,9 @@ object CatanInteraction {
             BuildKind.RAID -> BoardTargets(
                 hexes = legal.filterIsInstance<RaidFortress>().mapNotNull { state.topo.hexIndex[it.hex] }.toSet(),
             )
+            BuildKind.DIG -> BoardTargets(
+                hexes = legal.filterIsInstance<DigCanal>().mapNotNull { state.topo.hexIndex[it.hex] }.toSet(),
+            )
             BuildKind.WONDER -> BoardTargets()
             BuildKind.SETTLEMENT ->
                 BoardTargets(vertices = legal.filterIsInstance<BuildSettlement>().map { it.vertex }.toSet())
@@ -546,7 +554,7 @@ object CatanInteraction {
         val coord = topo.HEXES.getOrNull(hex) ?: return TapOutcome.Ignored
         val moves = legal.filterIsInstance<MoveRobber>().filter { it.hex == coord }
         val pirates = legal.filterIsInstance<MovePirate>().filter { it.hex == coord }
-        legal.firstOrNull { it is RaidFortress && it.hex == coord }?.let { return TapOutcome.Submit(it) }
+        legal.firstOrNull { (it is RaidFortress && it.hex == coord) || (it is DigCanal && it.hex == coord) }?.let { return TapOutcome.Submit(it) }
         return when {
             moves.isNotEmpty() -> if (moves.size == 1) {
                 TapOutcome.Submit(moves.first())
@@ -615,6 +623,7 @@ object CatanInteraction {
         if (legal.any { it is BuildSettlement }) add(BuildKind.SETTLEMENT)
         if (legal.any { it is BuildCity }) add(BuildKind.CITY)
         if (legal.any { it is RaidFortress }) add(BuildKind.RAID)
+        if (legal.any { it is DigCanal }) add(BuildKind.DIG)
         if (legal.any { it is BuildWonder }) add(BuildKind.WONDER)
         if (legal.any { it is BuildWall }) add(BuildKind.WALL)
         if (legal.any { it is HireKnight }) add(BuildKind.KNIGHT)

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

@@ -601,6 +601,7 @@ private fun buildLabel(kind: BuildKind): String = when (kind) {
     BuildKind.KNIGHT -> CatanText.KNIGHT
     BuildKind.SHIP -> CatanText.SHIP
     BuildKind.RAID -> CatanText.RAID
+    BuildKind.DIG -> CatanText.DIG
     BuildKind.WONDER -> CatanText.WONDER
 }
 
@@ -612,6 +613,7 @@ private fun buildCost(kind: BuildKind): String = when (kind) {
     BuildKind.KNIGHT -> CatanText.KNIGHT_COST
     BuildKind.SHIP -> CatanText.SHIP_COST_TEXT
     BuildKind.RAID -> CatanText.RAID_COST
+    BuildKind.DIG -> CatanText.DIG_COST
     BuildKind.WONDER -> CatanText.WONDER_COST
 }
 
@@ -646,6 +648,7 @@ private fun seaAwards(state: CatanState, seat: Int, compact: Boolean): List<Stri
     val sea = state.sea ?: return emptyList()
     return buildList {
         if (sea.cloth.isNotEmpty()) add(if (compact) "${sea.cloth[seat]}c" else "Cloth ${sea.cloth[seat]}")
+        if (sea.canalDug.isNotEmpty()) add(if (compact) "${sea.canalDug[seat]}⛏" else "Dug ${sea.canalDug[seat]}")
         if (sea.wonders.isNotEmpty()) add(if (compact) "W${sea.wonders[seat]}" else "Wonder ${sea.wonders[seat]}/4")
         if (seat in sea.harbourSeats) add(if (compact) "3:1" else "Harbour 3:1")
     }

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

@@ -118,6 +118,8 @@ object CatanText {
     const val SHIP_COST_TEXT = "1 lumber + 1 wool"
     const val RAID = "Raid"
     const val RAID_COST = "1 ore + 1 wool + 1 grain"
+    const val DIG = "Dig"
+    const val DIG_COST = "1 brick + 1 ore"
     const val WONDER = "Wonder"
     const val WONDER_COST = "next stage"
     const val GOLD_TITLE = "Gold field"
@@ -254,6 +256,7 @@ object CatanText {
                 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.RAID -> "Tap a pirate fortress your ship lies beside to raid it."
+                building == BuildKind.DIG -> "Tap a canal tile beside one of your towns to dig a unit."
                 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."
@@ -459,6 +462,7 @@ object CatanText {
                 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.RAID -> "Tap a pirate fortress your ship lies beside to raid it."
+                building == BuildKind.DIG -> "Tap a canal tile beside one of your towns to dig a unit."
                 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/CatanSeaExtrasTest.kt

@@ -241,4 +241,96 @@ class CatanSeaExtrasTest {
         val s = wonderGame().copy(resources = List(3) { Resource.entries.associateWith { 0 } })
         assertTrue(CatanRules.legalMoves(s, 0).none { it is BuildWonder })
     }
+
+    // ---- Treasure Islands, Oases ----
+
+    @Test
+    fun `chests lie under the fog and are hidden from other views`() {
+        for (scenario in listOf(SeaScenario.TREASURE_ISLANDS, SeaScenario.OASES)) {
+            val s = start(scenario)
+            val chests = s.sea!!.treasures.indices.filter { s.sea!!.treasures[it] != Treasure.NONE }
+            assertEquals(minOf(5, s.terrains.count { it == Terrain.FOG }), chests.size)
+            assertTrue(chests.all { s.terrains[it] == Terrain.FOG })
+            assertTrue(CatanRules.viewFor(s, 1).sea!!.treasures.isEmpty())
+        }
+    }
+
+    @Test
+    fun `an oasis map starts everyone on the desert island, never beside an oasis`() {
+        val s = start(SeaScenario.OASES)
+        assertEquals(37, s.topo.islandOf.count { it == s.sea!!.home })
+        val moves = CatanRules.legalMoves(s.copy(phase = CatanPhase.SETUP_FIRST), s.firstSeat).filterIsInstance<SetupPlace>()
+        assertTrue(moves.isNotEmpty())
+        assertTrue(moves.all { m -> s.topo.VERTEX_HEXES[m.vertex].none { s.terrains[it] == Terrain.FOG } })
+    }
+
+    /** A chest of [kind] under the first fog hex, with a road of seat 0's laid up to the edge that will reveal it. */
+    private fun chestGame(kind: Treasure): Triple<CatanState, Int, Int> {
+        val s = start(SeaScenario.OASES).copy(phase = CatanPhase.PLAYING)
+        val topo = s.topo
+        val hex = s.terrains.indexOf(Terrain.FOG)
+        val chests = List(topo.HEX_COUNT) { if (it == hex) kind else Treasure.NONE }
+        // Seat 0 owns the town beside a road that reaches the oasis; building the road finds it.
+        val edge = topo.EDGE_VERTICES.indices.first { e -> hex in topo.EDGE_HEXES[e] && topo.edgeLand[e] }
+        val staged = s.copy(
+            resources = List(3) { Resource.entries.associateWith { 5 } },
+            sea = s.sea!!.copy(treasures = chests),
+        )
+        return Triple(staged, hex, edge)
+    }
+
+    @Test
+    fun `opening a chest pays its reward`() {
+        val kinds = listOf(Treasure.BRICK_WOOL_GRAIN, Treasure.ROADS, Treasure.DEV_CARD, Treasure.CHOICE)
+        for (kind in kinds) {
+            val (s, _, _) = chestGame(kind)
+            // Stage the find directly: reveal as if a road had just reached the hex.
+            val topo = s.topo
+            val hex = s.terrains.indexOf(Terrain.FOG)
+            val edge = (0 until topo.EDGE_COUNT).first { hex in topo.EDGE_HEXES[it] && topo.edgeLand[it] }
+            val after = SeaRules.reveal(s, 0, edge)
+            assertTrue("$kind: the chest is announced", after.log.any { "treasure chest" in it })
+            when (kind) {
+                Treasure.DEV_CARD -> assertEquals(1, after.devHands[0].size)
+                Treasure.CHOICE -> assertTrue(after.phase == CatanPhase.GOLD || after.log.any { "uncovers" in it })
+                Treasure.ROADS -> assertTrue(after.resources[0].getValue(Resource.LUMBER) >= 7)
+                else -> assertTrue(after.resources[0].getValue(Resource.WOOL) >= 6)
+            }
+        }
+    }
+
+    // ---- The Great Canal ----
+
+    private fun canalGame(): Triple<CatanState, Int, CatanState> {
+        val s = start(SeaScenario.GREAT_CANAL).copy(
+            phase = CatanPhase.PLAYING,
+            resources = List(3) { Resource.entries.associateWith { 9 } },
+        )
+        val tile = s.sea!!.canalNumbers.indexOfFirst { it != 0 }
+        val staged = s.copy(
+            buildings = s.buildings.toMutableList().also {
+                it[s.topo.HEX_CORNERS[tile][0]] = CatanBuilding(BuildingType.SETTLEMENT, 0)
+            },
+        )
+        return Triple(staged, tile, s)
+    }
+
+    @Test
+    fun `a canal tile hides its number, and three digs turn it into fields`() {
+        var (s, tile, _) = canalGame()
+        assertEquals(0, s.numbers[tile])
+        assertEquals(Terrain.DESERT, s.terrains[tile])
+        val number = s.sea!!.canalNumbers[tile]
+        val dig = DigCanal(s.topo.HEXES[tile])
+        assertTrue(dig in CatanRules.legalMoves(s, 0))
+        assertTrue(CatanRules.legalMoves(s.copy(turn = 1), 1).none { it is DigCanal })
+        val before = CatanRules.publicVictoryPoints(s)[0]
+        repeat(2) { s = CatanRules.applyMove(s, 0, dig) }
+        assertEquals(Terrain.DESERT, s.terrains[tile])
+        assertEquals(before + 1, CatanRules.publicVictoryPoints(s)[0])
+        s = CatanRules.applyMove(s, 0, dig)
+        assertEquals(Terrain.FIELDS, s.terrains[tile])
+        assertEquals(number, s.numbers[tile])
+        assertTrue(CatanRules.legalMoves(s, 0).none { it is DigCanal && it.hex == dig.hex })
+    }
 }

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

@@ -43,6 +43,9 @@ class CatanSeaScenariosTest {
         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(1, 3, 4, 15), sizes(SeaScenario.TREASURE_ISLANDS))
+        assertEquals(listOf(37), sizes(SeaScenario.OASES))
+        assertEquals(listOf(2, 25), sizes(SeaScenario.GREAT_CANAL))
         assertEquals(listOf(4, 5, 18), sizes(SeaScenario.PIRATE_ISLANDS))
         assertEquals(listOf(1, 3, 12, 13), sizes(SeaScenario.WONDERS_OF_CATAN))
         assertEquals(listOf(2, 3, 6, 17), sizes(SeaScenario.CLOTH_FOR_CATAN))
@@ -64,7 +67,8 @@ class CatanSeaScenariosTest {
                     assertEquals("$scenario hex $h", land && !unnumbered, s.numbers[h] != 0)
                 }
                 val deserted = scenario != SeaScenario.FOUR_ISLANDS && scenario != SeaScenario.CLOTH_FOR_CATAN &&
-                    scenario != SeaScenario.FORGOTTEN_TRIBE && scenario != SeaScenario.PIRATE_ISLANDS
+                    scenario != SeaScenario.FORGOTTEN_TRIBE && scenario != SeaScenario.PIRATE_ISLANDS &&
+                    scenario != SeaScenario.TREASURE_ISLANDS
                 assertTrue("$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 }
@@ -219,6 +223,8 @@ class CatanSeaScenariosTest {
         var chipsTaken = 0
         var fortsTaken = 0
         var wonderStages = 0
+        var chestsOpened = 0
+        var canalDug = 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)
@@ -238,6 +244,10 @@ class CatanSeaScenariosTest {
                 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.PIRATE_ISLANDS) fortsTaken += state.sea!!.raidPoints.sum() / 2
+                if (scenario == SeaScenario.TREASURE_ISLANDS || scenario == SeaScenario.OASES) {
+                    chestsOpened += state.log.count { "treasure chest" in it }
+                }
+                if (scenario == SeaScenario.GREAT_CANAL) canalDug += state.sea!!.canalDug.sum()
                 if (scenario == SeaScenario.WONDERS_OF_CATAN) wonderStages += state.sea!!.wonders.sum()
                 if (scenario == SeaScenario.FORGOTTEN_TRIBE) {
                     chipsTaken += 4 - state.sea!!.chips.count { it != TribeChip.NONE }
@@ -249,6 +259,8 @@ class CatanSeaScenariosTest {
         assertTrue("no village ever paid cloth", clothPaid > 0)
         assertTrue("no tribe chip was ever taken", chipsTaken > 0)
         assertTrue("no fortress ever fell", fortsTaken > 0)
+        assertTrue("no chest was ever opened", chestsOpened > 0)
+        assertTrue("no canal unit was ever dug", canalDug > 0)
         assertTrue("no wonder stage was ever built", wonderStages > 0)
     }
 }

docs/RE-catan-universe.md

@@ -66,7 +66,13 @@ A full-width panel that slides up over the bottom of the screen (`Animator`, col
 * **Fog islands:** `Check_FogField`, `DistributeFogField` (hidden hex revealed when a
   road/ship reaches it, the player takes the resource), `Shuffle_Islands`, `Shuffle_TileValueList`.
 * **Treasure islands / Oasis / Great Canal** are Catan Universe scenario extras and are
-  **not** part of the physical Seafarers rules; they are out of scope here.
+  **not** part of the physical Seafarers rules. Names and texts only (rule values are compiled code):
+  `TreasureRule` with chest outcomes (bricks, wool, grain; a resource; a development card; two roads),
+  `SeafarerOasis` (no rule class of its own, base-game rules), and `GreatCanalRule` with `BuildCanal`,
+  `CanalVictoryPoints`, "The canal was completely dug. Now grain can be grown." and a target of 21 / 18 points.
+  The base-game scenario `baseharbormaster`: "2 victory points. This card goes to the first player to acquire at
+  least 3 harbors. If another player acquires more, he will immediately receive this card."
+  Implemented as inferred rules; see `docs/RULES-catan-seafarers.md`.
 * **Setup:** `StartPhase_BuildSettlement`, `StartPhase_BuildRoadShip`, `PlaceValueChip`
   (number tokens placed per scenario), `Shuffle_Harbors`.
 * **Island bonus:** special victory points for the first settlement on a new island

docs/RULES-catan-seafarers.md

@@ -36,6 +36,11 @@ Pick the map at setup; each scenario names where the starting settlements may go
   fortress. See *Pirate Islands* below.
 * **Wonders of Catan.** A 13-hex island with a desert, a 12-hex island, and gold islets. See *Wonders* below.
 
+* **The Treasure Islands** *(Catan Universe extra)*. A 15-hex home island and four fog isles, eight hexes of fog in
+  all. See *Catan Universe extras* below.
+* **The Oases** *(Catan Universe extra)*. One 37-hex island that is mostly desert, with three oases hidden in it.
+* **The Great Canal** *(Catan Universe extra)*. A 25-hex island split by a row of five canal tiles, and gold islets.
+
 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,
@@ -139,6 +144,30 @@ board. Each stage is one move costing cards (stage 1: 2 brick, 1 lumber, 1 grain
 1 grain, 1 lumber; 4: 3 ore, 2 grain, 1 brick). Each stage built is **one victory point**, and the seat that
 builds the fourth stage **wins at once**, whatever the point target. Wonders are not shared: each seat has its own.
 
+## Catan Universe extras (inferred)
+
+These three exist in the Catan Universe app but not in the physical set. Only their names, menu texts and log
+lines could be read (`docs/RE-catan-universe.md`); the rule values are compiled code that was not recovered. **Every
+rule below is inferred from those names and texts**, not copied.
+
+* **Treasure Islands.** The app's text: "Treasures await the Catanians on neighboring, fog-covered islands.
+  Discoveries are rewarded!" Its chest rewards (log texts and action names) are bricks, wool and grain; a resource of
+  choice; a development card; two roads. Here: up to five chests are dealt face down to random fog hexes at the
+  start. A seat that uncovers the hex (the fog rules) opens the chest at once and takes: *a brick, a wool and a grain*;
+  *one resource of its choice* (a gold pick); *a development card* (a resource of choice if the deck is empty or it is
+  Cities & Knights, which has no deck); or *two lumber and two brick* standing in for two free roads (the free-roads
+  phase would have to nest inside a ship move). The app's Cities & Knights version gives a progress card; that is
+  not modelled. The app's fixed treasure bonus (`SEAFARER_TREASURE_BONUS`) is not modelled either.
+* **The Oases.** The app's text: an enormous desert with rumoured oases and treasures, base-game rules. Here: the
+  oases are fog hexes inside the desert, uncovered by a road reaching them, and hold the same chests as above.
+  There is no ship rule on the map itself.
+* **The Great Canal.** The app's text, for Cities & Knights plus Seafarers: build a canal; first to 21 (3 players) or
+  18 (4 players) wins; the canal's parts earn victory points; when a tile is dug out, grain grows there. Its knights dig
+  in the app; here digging is cheaper to implement and play without Cities & Knights: a canal tile is a desert hex with
+  its number token hidden. A seat with a settlement or city on a corner of the tile digs one **unit** for 1 brick and
+  1 ore; **three units** finish the tile, which becomes **fields** with the hidden number. Every **two units** a seat
+  has dug are a **victory point**. The app's gold river, harbour changes and target scores are not modelled.
+
 ## With Cities & Knights
 
 Switching both expansions on plays [Cities & Knights](RULES-catan-ck.md) on any Seafarers map
@@ -161,8 +190,10 @@ Where the two meet, this game decides as follows:
 ## Not included
 
 The physical expansion has more scenarios and the Catan Universe app adds more still. These are **out of scope here**:
-treasure islands, the oasis, the great canal, the Explorers & Pirates combination,
+the Explorers & Pirates combination,
 the printed rules of the wonders and pirate-islands scenarios (the versions here are simplified) and trade ships.
+Drought and the app's other scenarios (Six Islands, Oceania, Great Catan, Enchanted Land, the Inka and Big Game sets)
+are not built.
 A map-only scenario is a new text map and a new `SeaScenario` entry.
 
 ## How the AI plays it