diff --git a/src/core/game/GameMap.ts b/src/core/game/GameMap.ts
new file mode 100644
index 000000000..baec41eac
--- /dev/null
+++ b/src/core/game/GameMap.ts
@@ -0,0 +1,209 @@
+import { TerrainType } from "./Game";
+
+export type TileRef = number;
+
+export class GameMap {
+    private tiles: bigint[] = [];
+    private width_: number;
+    private height_: number;
+    private numLandTiles_: number = 0;
+
+    // Bit positions for tile data
+    private static readonly FALLOUT_BIT = 0n;
+    private static readonly OCEAN_BIT = 1n;
+    private static readonly SHORELINE_BIT = 2n;
+    private static readonly IS_LAND_BIT = 3n;
+    private static readonly IS_BORDER_BIT = 4n;
+    private static readonly HAS_DEFENSE_BONUS_BIT = 5n;
+
+    private static readonly MAGNITUDE_OFFSET = 8n;
+    private static readonly MAGNITUDE_BITS = 5n;
+    private static readonly MAGNITUDE_MASK = (1n << GameMap.MAGNITUDE_BITS) - 1n;
+
+    private static readonly PLAYER_ID_OFFSET = 13n;
+    private static readonly PLAYER_ID_BITS = 12n;
+    private static readonly PLAYER_ID_MASK = (1n << GameMap.PLAYER_ID_BITS) - 1n;
+
+    private static readonly X_COORD_OFFSET = 25n;
+    private static readonly X_COORD_BITS = 12n;
+    private static readonly X_COORD_MASK = (1n << GameMap.X_COORD_BITS) - 1n;
+
+    private static readonly Y_COORD_OFFSET = 37n;
+    private static readonly Y_COORD_BITS = 12n;
+    private static readonly Y_COORD_MASK = (1n << GameMap.Y_COORD_BITS) - 1n;
+
+    constructor(width: number, height: number) {
+        this.width_ = width;
+        this.height_ = height;
+        this.tiles = new Array(width * height).fill(0n);
+    }
+
+    // Get reference from coordinates
+    ref(x: number, y: number): TileRef {
+        if (!this.isValidCoord(x, y)) {
+            throw new Error(`Invalid coordinates: ${x},${y}`);
+        }
+        return y * this.width_ + x;
+    }
+
+    // Basic properties
+    width(): number { return this.width_; }
+    height(): number { return this.height_; }
+    numLandTiles(): number { return this.numLandTiles_; }
+
+    // Coordinate validation
+    isValidCoord(x: number, y: number): boolean {
+        return x >= 0 && x < this.width_ && y >= 0 && y < this.height_;
+    }
+
+    // Get coordinates from reference
+    x(ref: TileRef): number {
+        return Number((this.tiles[ref] >> GameMap.X_COORD_OFFSET) & GameMap.X_COORD_MASK);
+    }
+
+    y(ref: TileRef): number {
+        return Number((this.tiles[ref] >> GameMap.Y_COORD_OFFSET) & GameMap.Y_COORD_MASK);
+    }
+
+    // Tile property getters
+    playerId(ref: TileRef): number {
+        return Number((this.tiles[ref] >> GameMap.PLAYER_ID_OFFSET) & GameMap.PLAYER_ID_MASK);
+    }
+
+    magnitude(ref: TileRef): number {
+        return Number((this.tiles[ref] >> GameMap.MAGNITUDE_OFFSET) & GameMap.MAGNITUDE_MASK);
+    }
+
+    isLand(ref: TileRef): boolean {
+        return Boolean(this.tiles[ref] & (1n << GameMap.IS_LAND_BIT));
+    }
+
+    isOcean(ref: TileRef): boolean {
+        return Boolean(this.tiles[ref] & (1n << GameMap.OCEAN_BIT));
+    }
+
+    isShoreline(ref: TileRef): boolean {
+        return Boolean(this.tiles[ref] & (1n << GameMap.SHORELINE_BIT));
+    }
+
+    hasFallout(ref: TileRef): boolean {
+        return Boolean(this.tiles[ref] & (1n << GameMap.FALLOUT_BIT));
+    }
+
+    isBorder(ref: TileRef): boolean {
+        return Boolean(this.tiles[ref] & (1n << GameMap.IS_BORDER_BIT));
+    }
+
+    hasDefenseBonus(ref: TileRef): boolean {
+        return Boolean(this.tiles[ref] & (1n << GameMap.HAS_DEFENSE_BONUS_BIT));
+    }
+
+    // Tile property setters
+    setFallout(ref: TileRef, value: boolean): void {
+        if (value) {
+            this.tiles[ref] |= 1n << GameMap.FALLOUT_BIT;
+        } else {
+            this.tiles[ref] &= ~(1n << GameMap.FALLOUT_BIT);
+        }
+    }
+
+    setBorder(ref: TileRef, value: boolean): void {
+        if (value) {
+            this.tiles[ref] |= 1n << GameMap.IS_BORDER_BIT;
+        } else {
+            this.tiles[ref] &= ~(1n << GameMap.IS_BORDER_BIT);
+        }
+    }
+
+    setPlayerId(ref: TileRef, playerId: number): void {
+        const mask = GameMap.PLAYER_ID_MASK << GameMap.PLAYER_ID_OFFSET;
+        this.tiles[ref] = (this.tiles[ref] & ~mask) |
+            ((BigInt(playerId) & GameMap.PLAYER_ID_MASK) << GameMap.PLAYER_ID_OFFSET);
+    }
+
+    // Helper methods
+    isWater(ref: TileRef): boolean {
+        return !this.isLand(ref);
+    }
+
+    isLake(ref: TileRef): boolean {
+        return !this.isLand(ref) && !this.isOcean(ref);
+    }
+
+    isShore(ref: TileRef): boolean {
+        return this.isLand(ref) && this.isShoreline(ref);
+    }
+
+    cost(ref: TileRef): number {
+        return this.magnitude(ref) < 10 ? 2 : 1;
+    }
+
+    getTerrainType(ref: TileRef): TerrainType {
+        if (this.isLand(ref)) {
+            const magnitude = this.magnitude(ref);
+            if (magnitude < 10) return TerrainType.Plains;
+            if (magnitude < 20) return TerrainType.Highland;
+            return TerrainType.Mountain;
+        }
+        return this.isOcean(ref) ? TerrainType.Ocean : TerrainType.Lake;
+    }
+
+    // Get neighboring tiles
+    neighbors(ref: TileRef): TileRef[] {
+        const x = this.x(ref);
+        const y = this.y(ref);
+
+        return [
+            { x: x - 1, y },
+            { x: x + 1, y },
+            { x, y: y - 1 },
+            { x, y: y + 1 }
+        ]
+            .filter(pos => this.isValidCoord(pos.x, pos.y))
+            .map(pos => this.ref(pos.x, pos.y));
+    }
+
+    // Method to set initial tile data
+    setTile(
+        ref: TileRef,
+        x: number,
+        y: number,
+        playerId: number,
+        magnitude: number,
+        isLand: boolean = false,
+        isOcean: boolean = false,
+        hasFallout: boolean = false,
+        isShoreline: boolean = false,
+        isBorder: boolean = false,
+        hasDefenseBonus: boolean = false
+    ): void {
+        let tile = 0n;
+
+        // Set coordinates
+        tile |= (BigInt(x) & GameMap.X_COORD_MASK) << GameMap.X_COORD_OFFSET;
+        tile |= (BigInt(y) & GameMap.Y_COORD_MASK) << GameMap.Y_COORD_OFFSET;
+
+        // Set player ID
+        tile |= (BigInt(playerId) & GameMap.PLAYER_ID_MASK) << GameMap.PLAYER_ID_OFFSET;
+
+        // Set magnitude
+        tile |= (BigInt(magnitude) & GameMap.MAGNITUDE_MASK) << GameMap.MAGNITUDE_OFFSET;
+
+        // Set boolean flags
+        if (hasFallout) tile |= 1n << GameMap.FALLOUT_BIT;
+        if (isOcean) tile |= 1n << GameMap.OCEAN_BIT;
+        if (isShoreline) tile |= 1n << GameMap.SHORELINE_BIT;
+        if (isLand) {
+            tile |= 1n << GameMap.IS_LAND_BIT;
+            this.numLandTiles_++;
+        }
+        if (isBorder) tile |= 1n << GameMap.IS_BORDER_BIT;
+        if (hasDefenseBonus) tile |= 1n << GameMap.HAS_DEFENSE_BONUS_BIT;
+
+        this.tiles[ref] = tile;
+    }
+}
+
+export function createGameMap(width: number, height: number): GameMap {
+    return new GameMap(width, height);
+}
\ No newline at end of file