diff --git a/src/client/graphics/layers/TerritoryLayer.ts b/src/client/graphics/layers/TerritoryLayer.ts
index 94b27d886..eb354aa66 100644
--- a/src/client/graphics/layers/TerritoryLayer.ts
+++ b/src/client/graphics/layers/TerritoryLayer.ts
@@ -28,6 +28,7 @@ import {
   readTerritoryShaderId,
 } from "../webgpu/render/TerritoryShaderRegistry";
 import { TerritoryRenderer } from "../webgpu/TerritoryRenderer";
+import { TerritoryRendererProxy } from "../webgpu/TerritoryRendererProxy";
 import { Layer } from "./Layer";
 
 export class TerritoryLayer implements Layer {
@@ -42,7 +43,8 @@ export class TerritoryLayer implements Layer {
 
   private theme: Theme;
 
-  private territoryRenderer: TerritoryRenderer | null = null;
+  private territoryRenderer: TerritoryRenderer | TerritoryRendererProxy | null =
+    null;
   private alternativeView = false;
 
   private lastPaletteSignature: string | null = null;
@@ -119,9 +121,11 @@ export class TerritoryLayer implements Layer {
   }
 
   private configureRenderer() {
-    const { renderer, reason } = TerritoryRenderer.create(
+    // Use proxy to render in worker thread
+    const { renderer, reason } = TerritoryRendererProxy.create(
       this.game,
       this.theme,
+      this.game.worker,
     );
     if (!renderer) {
       throw new Error(reason ?? "WebGPU is required for territory rendering.");
@@ -189,6 +193,11 @@ export class TerritoryLayer implements Layer {
 
     const canvas = this.territoryRenderer.canvas;
 
+    // Canvas must be HTMLCanvasElement for DOM operations (proxy always provides this)
+    if (!(canvas instanceof HTMLCanvasElement)) {
+      return;
+    }
+
     // If the renderer recreated its canvas, detach the old one.
     if (this.attachedTerritoryCanvas !== canvas) {
       this.attachedTerritoryCanvas?.remove();
diff --git a/src/client/graphics/webgpu/TerritoryRendererProxy.ts b/src/client/graphics/webgpu/TerritoryRendererProxy.ts
new file mode 100644
index 000000000..b2fac5880
--- /dev/null
+++ b/src/client/graphics/webgpu/TerritoryRendererProxy.ts
@@ -0,0 +1,301 @@
+import { createCanvas } from "src/client/Utils";
+import { Theme } from "../../../core/configuration/Config";
+import { TileRef } from "../../../core/game/GameMap";
+import { GameView } from "../../../core/game/GameView";
+import { WorkerClient } from "../../../core/worker/WorkerClient";
+import {
+  InitRendererMessage,
+  MarkAllDirtyMessage,
+  MarkTileMessage,
+  RefreshPaletteMessage,
+  RefreshTerrainMessage,
+  RenderFrameMessage,
+  SetAlternativeViewMessage,
+  SetHighlightedOwnerMessage,
+  SetShaderSettingsMessage,
+  SetViewSizeMessage,
+  SetViewTransformMessage,
+  TickRendererMessage,
+} from "../../../core/worker/WorkerMessages";
+
+export interface TerritoryWebGLCreateResult {
+  renderer: TerritoryRendererProxy | null;
+  reason?: string;
+}
+
+/**
+ * Proxy for TerritoryRenderer that forwards calls to worker thread.
+ * Manages canvas transfer and message routing.
+ */
+export class TerritoryRendererProxy {
+  public readonly canvas: HTMLCanvasElement;
+  private offscreenCanvas: OffscreenCanvas | null = null;
+  private worker: WorkerClient | null = null;
+  private ready = false;
+  private initPromise: Promise<void> | null = null;
+  private pendingMessages: any[] = [];
+
+  private constructor(
+    private readonly game: GameView,
+    private readonly theme: Theme,
+  ) {
+    this.canvas = createCanvas();
+    this.canvas.style.pointerEvents = "none";
+    this.canvas.width = 1;
+    this.canvas.height = 1;
+  }
+
+  static create(
+    game: GameView,
+    theme: Theme,
+    worker: WorkerClient,
+  ): TerritoryWebGLCreateResult {
+    const nav = globalThis.navigator as any;
+    if (!nav?.gpu || typeof nav.gpu.requestAdapter !== "function") {
+      return {
+        renderer: null,
+        reason: "WebGPU not available; GPU renderer disabled.",
+      };
+    }
+
+    if (typeof OffscreenCanvas === "undefined") {
+      return {
+        renderer: null,
+        reason: "OffscreenCanvas not supported; GPU renderer disabled.",
+      };
+    }
+
+    const state = game.tileStateView();
+    const expected = game.width() * game.height();
+    if (state.length !== expected) {
+      return {
+        renderer: null,
+        reason: "Tile state buffer size mismatch; GPU renderer disabled.",
+      };
+    }
+
+    const renderer = new TerritoryRendererProxy(game, theme);
+    renderer.worker = worker;
+    renderer.startInit();
+    return { renderer };
+  }
+
+  private startInit(): void {
+    if (this.initPromise) return;
+    this.initPromise = this.init();
+  }
+
+  private async init(): Promise<void> {
+    if (!this.worker) {
+      throw new Error("Worker not set");
+    }
+
+    // Transfer canvas control to offscreen
+    this.offscreenCanvas = this.canvas.transferControlToOffscreen();
+
+    // Send init message to worker
+    // Determine dark mode from theme (check if it has darkShore property, same as GroundTruthData)
+    const themeAny = this.theme as any;
+    const darkMode = themeAny.darkShore !== undefined;
+
+    const messageId = `init_renderer_${Date.now()}`;
+    const initMessage: InitRendererMessage = {
+      type: "init_renderer",
+      id: messageId,
+      offscreenCanvas: this.offscreenCanvas,
+      darkMode: darkMode,
+    };
+
+    // Transfer the offscreen canvas
+    this.worker.postMessage(initMessage, [this.offscreenCanvas]);
+
+    // Wait for renderer ready
+    await new Promise<void>((resolve, reject) => {
+      const timeout = setTimeout(() => {
+        this.worker?.removeMessageHandler(messageId);
+        reject(new Error("Renderer initialization timeout"));
+      }, 10000);
+
+      const handler = (message: any) => {
+        if (message.type === "renderer_ready" && message.id === messageId) {
+          clearTimeout(timeout);
+          this.worker?.removeMessageHandler(messageId);
+          this.ready = true;
+          // Send any pending messages
+          for (const msg of this.pendingMessages) {
+            this.sendToWorker(msg);
+          }
+          this.pendingMessages = [];
+          resolve();
+        }
+      };
+
+      this.worker?.addMessageHandler(messageId, handler);
+    });
+  }
+
+  private sendToWorker(message: any): void {
+    if (!this.worker) {
+      return;
+    }
+    if (!this.ready) {
+      this.pendingMessages.push(message);
+      return;
+    }
+    this.worker.postMessage(message);
+  }
+
+  setViewSize(width: number, height: number): void {
+    const message: SetViewSizeMessage = {
+      type: "set_view_size",
+      width,
+      height,
+    };
+    this.sendToWorker(message);
+  }
+
+  setViewTransform(scale: number, offsetX: number, offsetY: number): void {
+    const message: SetViewTransformMessage = {
+      type: "set_view_transform",
+      scale,
+      offsetX,
+      offsetY,
+    };
+    this.sendToWorker(message);
+  }
+
+  setAlternativeView(enabled: boolean): void {
+    const message: SetAlternativeViewMessage = {
+      type: "set_alternative_view",
+      enabled,
+    };
+    this.sendToWorker(message);
+  }
+
+  setHighlightedOwnerId(ownerSmallId: number | null): void {
+    const message: SetHighlightedOwnerMessage = {
+      type: "set_highlighted_owner",
+      ownerSmallId,
+    };
+    this.sendToWorker(message);
+  }
+
+  setTerritoryShader(shaderPath: string): void {
+    const message: SetShaderSettingsMessage = {
+      type: "set_shader_settings",
+      territoryShader: shaderPath,
+    };
+    this.sendToWorker(message);
+  }
+
+  setTerrainShader(shaderPath: string): void {
+    const message: SetShaderSettingsMessage = {
+      type: "set_shader_settings",
+      terrainShader: shaderPath,
+    };
+    this.sendToWorker(message);
+  }
+
+  setTerritoryShaderParams(
+    params0: Float32Array | number[],
+    params1: Float32Array | number[],
+  ): void {
+    const message: SetShaderSettingsMessage = {
+      type: "set_shader_settings",
+      territoryShaderParams0: Array.from(params0),
+      territoryShaderParams1: Array.from(params1),
+    };
+    this.sendToWorker(message);
+  }
+
+  setTerrainShaderParams(
+    params0: Float32Array | number[],
+    params1: Float32Array | number[],
+  ): void {
+    const message: SetShaderSettingsMessage = {
+      type: "set_shader_settings",
+      terrainShaderParams0: Array.from(params0),
+      terrainShaderParams1: Array.from(params1),
+    };
+    this.sendToWorker(message);
+  }
+
+  setPreSmoothing(
+    enabled: boolean,
+    shaderPath: string,
+    params0: Float32Array | number[],
+  ): void {
+    const message: SetShaderSettingsMessage = {
+      type: "set_shader_settings",
+      preSmoothing: {
+        enabled,
+        shaderPath,
+        params0: Array.from(params0),
+      },
+    };
+    this.sendToWorker(message);
+  }
+
+  setPostSmoothing(
+    enabled: boolean,
+    shaderPath: string,
+    params0: Float32Array | number[],
+  ): void {
+    const message: SetShaderSettingsMessage = {
+      type: "set_shader_settings",
+      postSmoothing: {
+        enabled,
+        shaderPath,
+        params0: Array.from(params0),
+      },
+    };
+    this.sendToWorker(message);
+  }
+
+  markTile(tile: TileRef): void {
+    const message: MarkTileMessage = {
+      type: "mark_tile",
+      tile,
+    };
+    this.sendToWorker(message);
+  }
+
+  markAllDirty(): void {
+    const message: MarkAllDirtyMessage = {
+      type: "mark_all_dirty",
+    };
+    this.sendToWorker(message);
+  }
+
+  refreshPalette(): void {
+    const message: RefreshPaletteMessage = {
+      type: "refresh_palette",
+    };
+    this.sendToWorker(message);
+  }
+
+  markDefensePostsDirty(): void {
+    this.markAllDirty();
+  }
+
+  refreshTerrain(): void {
+    const message: RefreshTerrainMessage = {
+      type: "refresh_terrain",
+    };
+    this.sendToWorker(message);
+  }
+
+  tick(): void {
+    const message: TickRendererMessage = {
+      type: "tick_renderer",
+    };
+    this.sendToWorker(message);
+  }
+
+  render(): void {
+    const message: RenderFrameMessage = {
+      type: "render_frame",
+    };
+    this.sendToWorker(message);
+  }
+}
diff --git a/src/client/graphics/webgpu/core/WebGPUDevice.ts b/src/client/graphics/webgpu/core/WebGPUDevice.ts
index 27b587a7c..07df9cba7 100644
--- a/src/client/graphics/webgpu/core/WebGPUDevice.ts
+++ b/src/client/graphics/webgpu/core/WebGPUDevice.ts
@@ -19,10 +19,12 @@ export class WebGPUDevice {
 
   /**
    * Initialize WebGPU device and canvas context.
-   * @param canvas Canvas element to configure
+   * @param canvas Canvas element to configure (HTMLCanvasElement or OffscreenCanvas)
    * @returns WebGPUDevice instance or null if WebGPU is not available
    */
-  static async create(canvas: HTMLCanvasElement): Promise<WebGPUDevice | null> {
+  static async create(
+    canvas: HTMLCanvasElement | OffscreenCanvas,
+  ): Promise<WebGPUDevice | null> {
     const nav = globalThis.navigator as any;
     if (!nav?.gpu || typeof nav.gpu.requestAdapter !== "function") {
       return null;
diff --git a/src/core/worker/GameViewAdapter.ts b/src/core/worker/GameViewAdapter.ts
new file mode 100644
index 000000000..1c8fa0875
--- /dev/null
+++ b/src/core/worker/GameViewAdapter.ts
@@ -0,0 +1,165 @@
+import { Theme } from "../configuration/Config";
+import { Game, UnitType } from "../game/Game";
+import { GameUpdateViewData } from "../game/GameUpdates";
+import { GameView } from "../game/GameView";
+import { TerrainMapData } from "../game/TerrainMapLoader";
+
+/**
+ * Adapter that makes Game work as GameView for rendering purposes.
+ * Provides the interface that GroundTruthData and rendering passes need,
+ * without requiring the full GameView infrastructure.
+ */
+export class GameViewAdapter implements Partial<GameView> {
+  private tileStateCache: Uint16Array | null = null;
+  private terrainDataCache: Uint8Array | null = null;
+  private lastUpdate: GameUpdateViewData | null = null;
+
+  constructor(
+    private game: Game,
+    private mapData: TerrainMapData,
+    private theme: Theme,
+  ) {}
+
+  /**
+   * Update adapter with latest game update data.
+   * Invalidates caches so they're recomputed on next access.
+   */
+  update(gu: GameUpdateViewData): void {
+    this.lastUpdate = gu;
+    // Invalidate caches when updated
+    this.tileStateCache = null;
+    this.terrainDataCache = null;
+  }
+
+  config() {
+    return this.game.config();
+  }
+
+  width(): number {
+    return this.game.width();
+  }
+
+  height(): number {
+    return this.game.height();
+  }
+
+  x(tile: bigint): number {
+    return this.game.x(tile);
+  }
+
+  y(tile: bigint): number {
+    return this.game.y(tile);
+  }
+
+  units(...types: UnitType[]): any[] {
+    return this.game.units(...types);
+  }
+
+  /**
+   * Build tile state view from game.
+   * Cached until next update.
+   */
+  tileStateView(): Uint16Array {
+    if (this.tileStateCache) {
+      return this.tileStateCache;
+    }
+    // Build tile state from game
+    const width = this.game.width();
+    const height = this.game.height();
+    const state = new Uint16Array(width * height);
+    for (let y = 0; y < height; y++) {
+      for (let x = 0; x < width; x++) {
+        const tile = this.game.ref(x, y);
+        const owner = this.game.owner(tile);
+        const ownerId = owner ? owner.smallID() : 0;
+        const terrain = this.game.terrain(tile);
+        const terrainType = terrain.type();
+        const terrainMag = terrain.magnitude();
+        // Pack state: ownerId (12 bits) | terrainType (2 bits) | terrainMag (2 bits)
+        state[y * width + x] =
+          (ownerId & 0xfff) |
+          ((terrainType & 0x3) << 12) |
+          ((terrainMag & 0x3) << 14);
+      }
+    }
+    this.tileStateCache = state;
+    return state;
+  }
+
+  /**
+   * Build terrain data view from game.
+   * Cached until next update.
+   */
+  terrainDataView(): Uint8Array {
+    if (this.terrainDataCache) {
+      return this.terrainDataCache;
+    }
+    // Build terrain data from game
+    const width = this.game.width();
+    const height = this.game.height();
+    const terrainData = new Uint8Array(width * height);
+    for (let y = 0; y < height; y++) {
+      for (let x = 0; x < width; x++) {
+        const tile = this.game.ref(x, y);
+        const terrain = this.game.terrain(tile);
+        terrainData[y * width + x] = terrain.type();
+      }
+    }
+    this.terrainDataCache = terrainData;
+    return terrainData;
+  }
+
+  /**
+   * Convert Game players to PlayerView-like objects for rendering.
+   * Computes colors from theme directly (no PlayerView needed).
+   */
+  playerViews(): any[] {
+    const theme = this.game.config().theme();
+    return this.game.players().map((p) => {
+      // Get default colors from theme
+      const defaultTerritoryColor = theme.territoryColor(p as any);
+      const defaultBorderColor = theme.borderColor(defaultTerritoryColor);
+      const territoryRgb = defaultTerritoryColor.toRgb();
+      const borderRgb = defaultBorderColor.toRgb();
+
+      return {
+        smallID: () => p.smallID(),
+        territoryColor: () => ({
+          rgba: {
+            r: Math.round(territoryRgb.r),
+            g: Math.round(territoryRgb.g),
+            b: Math.round(territoryRgb.b),
+            a: Math.round((territoryRgb.a ?? 1) * 255),
+          },
+        }),
+        borderColor: () => ({
+          rgba: {
+            r: Math.round(borderRgb.r),
+            g: Math.round(borderRgb.g),
+            b: Math.round(borderRgb.b),
+            a: Math.round((borderRgb.a ?? 1) * 255),
+          },
+        }),
+      };
+    });
+  }
+
+  /**
+   * Get my player for highlighting (returns null in worker context).
+   */
+  myPlayer(): any | null {
+    // Return null for now - this is used for highlighting
+    // Could be implemented if we track clientID in worker
+    return null;
+  }
+
+  /**
+   * Get recently updated tiles from last game update.
+   */
+  recentlyUpdatedTiles(): bigint[] {
+    if (!this.lastUpdate) {
+      return [];
+    }
+    return Array.from(this.lastUpdate.packedTileUpdates);
+  }
+}
diff --git a/src/core/worker/Worker.worker.ts b/src/core/worker/Worker.worker.ts
index a60e63e4b..f1eb5e755 100644
--- a/src/core/worker/Worker.worker.ts
+++ b/src/core/worker/Worker.worker.ts
@@ -1,7 +1,12 @@
 import version from "resources/version.txt?raw";
-import { createGameRunner, GameRunner } from "../GameRunner";
+import { Theme } from "../configuration/Config";
+import { PastelTheme } from "../configuration/PastelTheme";
+import { PastelThemeDark } from "../configuration/PastelThemeDark";
 import { FetchGameMapLoader } from "../game/FetchGameMapLoader";
 import { ErrorUpdate, GameUpdateViewData } from "../game/GameUpdates";
+import { loadTerrainMap, TerrainMapData } from "../game/TerrainMapLoader";
+import { createGameRunner, GameRunner } from "../GameRunner";
+import { GameStartInfo } from "../Schemas";
 import {
   AttackAveragePositionResultMessage,
   InitializedMessage,
@@ -9,19 +14,28 @@ import {
   PlayerActionsResultMessage,
   PlayerBorderTilesResultMessage,
   PlayerProfileResultMessage,
+  RendererReadyMessage,
   TransportShipSpawnResultMessage,
   WorkerMessage,
 } from "./WorkerMessages";
+import { WorkerTerritoryRenderer } from "./WorkerTerritoryRenderer";
 
 const ctx: Worker = self as any;
 let gameRunner: Promise<GameRunner> | null = null;
+let gameStartInfo: GameStartInfo | null = null;
 const mapLoader = new FetchGameMapLoader(`/maps`, version);
+let renderer: WorkerTerritoryRenderer | null = null;
+let mapData: TerrainMapData | null = null;
 
 function gameUpdate(gu: GameUpdateViewData | ErrorUpdate) {
   // skip if ErrorUpdate
   if (!("updates" in gu)) {
     return;
   }
+  // Update renderer with game update
+  if (renderer) {
+    renderer.updateGameView(gu);
+  }
   sendMessage({
     type: "game_update",
     gameUpdate: gu,
@@ -41,6 +55,7 @@ ctx.addEventListener("message", async (e: MessageEvent<MainThreadMessage>) => {
       break;
     case "init":
       try {
+        gameStartInfo = message.gameStartInfo;
         gameRunner = createGameRunner(
           message.gameStartInfo,
           message.clientID,
@@ -170,6 +185,153 @@ ctx.addEventListener("message", async (e: MessageEvent<MainThreadMessage>) => {
         console.error("Failed to spawn transport ship:", error);
       }
       break;
+
+    case "init_renderer":
+      try {
+        if (!gameRunner || !gameStartInfo) {
+          throw new Error("Game runner not initialized");
+        }
+        const gr = await gameRunner;
+
+        // Load map data if not already loaded
+        // Use gameStartInfo.config which has the original game map info
+        mapData ??= await loadTerrainMap(
+          gameStartInfo.config.gameMap,
+          gameStartInfo.config.gameMapSize,
+          mapLoader,
+        );
+
+        // Create theme based on darkMode flag from main thread
+        // (can't access userSettings in worker, so it's passed from main thread)
+        const theme: Theme = message.darkMode
+          ? new PastelThemeDark()
+          : new PastelTheme();
+
+        renderer = new WorkerTerritoryRenderer();
+
+        await renderer.init(message.offscreenCanvas, gr, mapData, theme);
+
+        sendMessage({
+          type: "renderer_ready",
+          id: message.id,
+        } as RendererReadyMessage);
+      } catch (error) {
+        console.error("Failed to initialize renderer:", error);
+        sendMessage({
+          type: "renderer_ready",
+          id: message.id,
+        } as RendererReadyMessage);
+        throw error;
+      }
+      break;
+
+    case "set_view_size":
+      if (renderer) {
+        renderer.setViewSize(message.width, message.height);
+      }
+      break;
+
+    case "set_view_transform":
+      if (renderer) {
+        renderer.setViewTransform(
+          message.scale,
+          message.offsetX,
+          message.offsetY,
+        );
+      }
+      break;
+
+    case "set_alternative_view":
+      if (renderer) {
+        renderer.setAlternativeView(message.enabled);
+      }
+      break;
+
+    case "set_highlighted_owner":
+      if (renderer) {
+        renderer.setHighlightedOwnerId(message.ownerSmallId);
+      }
+      break;
+
+    case "set_shader_settings":
+      if (renderer) {
+        if (message.territoryShader) {
+          renderer.setTerritoryShader(message.territoryShader);
+        }
+        if (message.territoryShaderParams0 && message.territoryShaderParams1) {
+          renderer.setTerritoryShaderParams(
+            message.territoryShaderParams0,
+            message.territoryShaderParams1,
+          );
+        }
+        if (message.terrainShader) {
+          renderer.setTerrainShader(message.terrainShader);
+        }
+        if (message.terrainShaderParams0 && message.terrainShaderParams1) {
+          renderer.setTerrainShaderParams(
+            message.terrainShaderParams0,
+            message.terrainShaderParams1,
+          );
+        }
+        if (message.preSmoothing) {
+          renderer.setPreSmoothing(
+            message.preSmoothing.enabled,
+            message.preSmoothing.shaderPath,
+            message.preSmoothing.params0,
+          );
+        }
+        if (message.postSmoothing) {
+          renderer.setPostSmoothing(
+            message.postSmoothing.enabled,
+            message.postSmoothing.shaderPath,
+            message.postSmoothing.params0,
+          );
+        }
+      }
+      break;
+
+    case "mark_tile":
+      if (renderer) {
+        renderer.markTile(message.tile);
+      }
+      break;
+
+    case "mark_all_dirty":
+      if (renderer) {
+        renderer.markAllDirty();
+      }
+      break;
+
+    case "refresh_palette":
+      if (renderer) {
+        renderer.refreshPalette();
+      }
+      break;
+
+    case "refresh_terrain":
+      if (renderer) {
+        renderer.refreshTerrain();
+      }
+      break;
+
+    case "tick_renderer":
+      if (renderer) {
+        const start = performance.now();
+        renderer.tick();
+        const computeMs = performance.now() - start;
+        sendMessage({
+          type: "renderer_metrics",
+          computeMs,
+        });
+      }
+      break;
+
+    case "render_frame":
+      if (renderer) {
+        renderer.render();
+      }
+      break;
+
     default:
       console.warn("Unknown message :", message);
   }
diff --git a/src/core/worker/WorkerClient.ts b/src/core/worker/WorkerClient.ts
index e6e80b82d..a5ea358dd 100644
--- a/src/core/worker/WorkerClient.ts
+++ b/src/core/worker/WorkerClient.ts
@@ -46,6 +46,7 @@ export class WorkerClient {
         break;
 
       case "initialized":
+      case "renderer_ready":
       default:
         if (message.id && this.messageHandlers.has(message.id)) {
           const handler = this.messageHandlers.get(message.id)!;
@@ -56,6 +57,30 @@ export class WorkerClient {
     }
   }
 
+  /**
+   * Add a message handler for a specific message ID.
+   */
+  addMessageHandler(
+    id: string,
+    handler: (message: WorkerMessage) => void,
+  ): void {
+    this.messageHandlers.set(id, handler);
+  }
+
+  /**
+   * Remove a message handler.
+   */
+  removeMessageHandler(id: string): void {
+    this.messageHandlers.delete(id);
+  }
+
+  /**
+   * Post a message to the worker with optional transferables.
+   */
+  postMessage(message: any, transfer?: Transferable[]): void {
+    this.worker.postMessage(message, transfer);
+  }
+
   initialize(): Promise<void> {
     return new Promise((resolve, reject) => {
       const messageId = generateID();
diff --git a/src/core/worker/WorkerMessages.ts b/src/core/worker/WorkerMessages.ts
index a8d30e9b1..158bb171d 100644
--- a/src/core/worker/WorkerMessages.ts
+++ b/src/core/worker/WorkerMessages.ts
@@ -23,7 +23,21 @@ export type WorkerMessageType =
   | "attack_average_position"
   | "attack_average_position_result"
   | "transport_ship_spawn"
-  | "transport_ship_spawn_result";
+  | "transport_ship_spawn_result"
+  | "init_renderer"
+  | "renderer_ready"
+  | "set_view_size"
+  | "set_view_transform"
+  | "set_alternative_view"
+  | "set_highlighted_owner"
+  | "set_shader_settings"
+  | "mark_tile"
+  | "mark_all_dirty"
+  | "refresh_palette"
+  | "refresh_terrain"
+  | "tick_renderer"
+  | "render_frame"
+  | "renderer_metrics";
 
 // Base interface for all messages
 interface BaseWorkerMessage {
@@ -112,6 +126,91 @@ export interface TransportShipSpawnResultMessage extends BaseWorkerMessage {
   result: TileRef | false;
 }
 
+// Renderer messages from main thread to worker
+export interface InitRendererMessage extends BaseWorkerMessage {
+  type: "init_renderer";
+  offscreenCanvas: OffscreenCanvas;
+  darkMode: boolean; // Whether to use dark theme
+}
+
+export interface SetViewSizeMessage extends BaseWorkerMessage {
+  type: "set_view_size";
+  width: number;
+  height: number;
+}
+
+export interface SetViewTransformMessage extends BaseWorkerMessage {
+  type: "set_view_transform";
+  scale: number;
+  offsetX: number;
+  offsetY: number;
+}
+
+export interface SetAlternativeViewMessage extends BaseWorkerMessage {
+  type: "set_alternative_view";
+  enabled: boolean;
+}
+
+export interface SetHighlightedOwnerMessage extends BaseWorkerMessage {
+  type: "set_highlighted_owner";
+  ownerSmallId: number | null;
+}
+
+export interface SetShaderSettingsMessage extends BaseWorkerMessage {
+  type: "set_shader_settings";
+  territoryShader?: string;
+  territoryShaderParams0?: number[];
+  territoryShaderParams1?: number[];
+  terrainShader?: string;
+  terrainShaderParams0?: number[];
+  terrainShaderParams1?: number[];
+  preSmoothing?: {
+    enabled: boolean;
+    shaderPath: string;
+    params0: number[];
+  };
+  postSmoothing?: {
+    enabled: boolean;
+    shaderPath: string;
+    params0: number[];
+  };
+}
+
+export interface MarkTileMessage extends BaseWorkerMessage {
+  type: "mark_tile";
+  tile: TileRef;
+}
+
+export interface MarkAllDirtyMessage extends BaseWorkerMessage {
+  type: "mark_all_dirty";
+}
+
+export interface RefreshPaletteMessage extends BaseWorkerMessage {
+  type: "refresh_palette";
+}
+
+export interface RefreshTerrainMessage extends BaseWorkerMessage {
+  type: "refresh_terrain";
+}
+
+export interface TickRendererMessage extends BaseWorkerMessage {
+  type: "tick_renderer";
+}
+
+export interface RenderFrameMessage extends BaseWorkerMessage {
+  type: "render_frame";
+}
+
+// Renderer messages from worker to main thread
+export interface RendererReadyMessage extends BaseWorkerMessage {
+  type: "renderer_ready";
+}
+
+export interface RendererMetricsMessage extends BaseWorkerMessage {
+  type: "renderer_metrics";
+  computeMs: number;
+}
+
 // Union types for type safety
 export type MainThreadMessage =
   | HeartbeatMessage
@@ -121,7 +220,19 @@ export type MainThreadMessage =
   | PlayerProfileMessage
   | PlayerBorderTilesMessage
   | AttackAveragePositionMessage
-  | TransportShipSpawnMessage;
+  | TransportShipSpawnMessage
+  | InitRendererMessage
+  | SetViewSizeMessage
+  | SetViewTransformMessage
+  | SetAlternativeViewMessage
+  | SetHighlightedOwnerMessage
+  | SetShaderSettingsMessage
+  | MarkTileMessage
+  | MarkAllDirtyMessage
+  | RefreshPaletteMessage
+  | RefreshTerrainMessage
+  | TickRendererMessage
+  | RenderFrameMessage;
 
 // Message send from worker
 export type WorkerMessage =
@@ -131,4 +242,6 @@ export type WorkerMessage =
   | PlayerProfileResultMessage
   | PlayerBorderTilesResultMessage
   | AttackAveragePositionResultMessage
-  | TransportShipSpawnResultMessage;
+  | TransportShipSpawnResultMessage
+  | RendererReadyMessage
+  | RendererMetricsMessage;
diff --git a/src/core/worker/WorkerTerritoryRenderer.ts b/src/core/worker/WorkerTerritoryRenderer.ts
new file mode 100644
index 000000000..cf137b3bc
--- /dev/null
+++ b/src/core/worker/WorkerTerritoryRenderer.ts
@@ -0,0 +1,603 @@
+import { Theme } from "../configuration/Config";
+import { TileRef } from "../game/GameMap";
+import { GameUpdateViewData } from "../game/GameUpdates";
+import { TerrainMapData } from "../game/TerrainMapLoader";
+import { GameRunner } from "../GameRunner";
+import { GameViewAdapter } from "./GameViewAdapter";
+
+// Import rendering components from client (they should work with adapter)
+import { ComputePass } from "../../client/graphics/webgpu/compute/ComputePass";
+import { DefendedStrengthFullPass } from "../../client/graphics/webgpu/compute/DefendedStrengthFullPass";
+import { DefendedStrengthPass } from "../../client/graphics/webgpu/compute/DefendedStrengthPass";
+import { StateUpdatePass } from "../../client/graphics/webgpu/compute/StateUpdatePass";
+import { TerrainComputePass } from "../../client/graphics/webgpu/compute/TerrainComputePass";
+import { VisualStateSmoothingPass } from "../../client/graphics/webgpu/compute/VisualStateSmoothingPass";
+import { GroundTruthData } from "../../client/graphics/webgpu/core/GroundTruthData";
+import { WebGPUDevice } from "../../client/graphics/webgpu/core/WebGPUDevice";
+import { RenderPass } from "../../client/graphics/webgpu/render/RenderPass";
+import { TemporalResolvePass } from "../../client/graphics/webgpu/render/TemporalResolvePass";
+import { TerritoryRenderPass } from "../../client/graphics/webgpu/render/TerritoryRenderPass";
+
+/**
+ * Worker-compatible WebGPU territory renderer.
+ * Works with Game directly (not GameView) and uses OffscreenCanvas.
+ */
+export class WorkerTerritoryRenderer {
+  private device: WebGPUDevice | null = null;
+  private resources: GroundTruthData | null = null;
+  private gameViewAdapter: GameViewAdapter | null = null;
+  private ready = false;
+
+  // Compute passes
+  private computePasses: ComputePass[] = [];
+  private computePassOrder: ComputePass[] = [];
+  private frameComputePasses: ComputePass[] = [];
+
+  // Render passes
+  private renderPasses: RenderPass[] = [];
+  private renderPassOrder: RenderPass[] = [];
+
+  // Pass instances
+  private terrainComputePass: TerrainComputePass | null = null;
+  private stateUpdatePass: StateUpdatePass | null = null;
+  private defendedStrengthFullPass: DefendedStrengthFullPass | null = null;
+  private defendedStrengthPass: DefendedStrengthPass | null = null;
+  private visualStateSmoothingPass: VisualStateSmoothingPass | null = null;
+  private territoryRenderPass: TerritoryRenderPass | null = null;
+  private temporalResolvePass: TemporalResolvePass | null = null;
+
+  private territoryShaderPath = "render/territory.wgsl";
+  private territoryShaderParams0 = new Float32Array(4);
+  private territoryShaderParams1 = new Float32Array(4);
+  private terrainShaderPath = "compute/terrain-compute.wgsl";
+  private terrainShaderParams0 = new Float32Array(4);
+  private terrainShaderParams1 = new Float32Array(4);
+  private preSmoothingShaderPath = "compute/visual-state-smoothing.wgsl";
+  private preSmoothingParams0 = new Float32Array(4);
+  private postSmoothingShaderPath = "render/temporal-resolve.wgsl";
+  private postSmoothingParams0 = new Float32Array(4);
+
+  private preSmoothingEnabled = false;
+  private postSmoothingEnabled = false;
+  private defensePostRange: number;
+
+  /**
+   * Initialize renderer with offscreen canvas and game data.
+   */
+  async init(
+    offscreenCanvas: OffscreenCanvas,
+    gameRunner: GameRunner,
+    mapData: TerrainMapData,
+    theme: Theme,
+  ): Promise<void> {
+    const game = gameRunner.game;
+    this.defensePostRange = game.config().defensePostRange();
+
+    // Create adapter
+    this.gameViewAdapter = new GameViewAdapter(game, mapData, theme);
+
+    // Initialize WebGPU device with offscreen canvas
+    const webgpuDevice = await WebGPUDevice.create(offscreenCanvas);
+    if (!webgpuDevice) {
+      throw new Error("Failed to create WebGPU device in worker");
+    }
+    this.device = webgpuDevice;
+
+    // Create ground truth data using adapter
+    const state = this.gameViewAdapter.tileStateView();
+    this.resources = GroundTruthData.create(
+      webgpuDevice.device,
+      this.gameViewAdapter as any,
+      theme,
+      state,
+    );
+    this.resources.setTerritoryShaderParams(
+      this.territoryShaderParams0,
+      this.territoryShaderParams1,
+    );
+    this.resources.setTerrainShaderParams(
+      this.terrainShaderParams0,
+      this.terrainShaderParams1,
+    );
+
+    // Upload terrain data and params
+    this.resources.uploadTerrainData();
+    this.resources.uploadTerrainParams();
+
+    // Create compute passes
+    this.terrainComputePass = new TerrainComputePass();
+    void this.terrainComputePass.setShader(this.terrainShaderPath);
+    this.stateUpdatePass = new StateUpdatePass();
+    this.defendedStrengthFullPass = new DefendedStrengthFullPass();
+    this.defendedStrengthPass = new DefendedStrengthPass();
+    this.visualStateSmoothingPass = new VisualStateSmoothingPass();
+
+    this.computePasses = [
+      this.terrainComputePass,
+      this.stateUpdatePass,
+      this.defendedStrengthFullPass,
+      this.defendedStrengthPass,
+    ];
+
+    this.frameComputePasses = [this.visualStateSmoothingPass];
+
+    // Create render passes
+    this.territoryRenderPass = new TerritoryRenderPass();
+    this.temporalResolvePass = new TemporalResolvePass();
+    this.renderPasses = [this.territoryRenderPass, this.temporalResolvePass];
+
+    // Initialize all passes
+    for (const pass of this.computePasses) {
+      await pass.init(webgpuDevice.device, this.resources);
+    }
+
+    for (const pass of this.frameComputePasses) {
+      await pass.init(webgpuDevice.device, this.resources);
+    }
+
+    for (const pass of this.renderPasses) {
+      await pass.init(
+        webgpuDevice.device,
+        this.resources,
+        webgpuDevice.canvasFormat,
+      );
+    }
+
+    if (this.territoryRenderPass) {
+      await this.territoryRenderPass.setShader(this.territoryShaderPath);
+    }
+
+    // Compute dependency order
+    this.computePassOrder = this.topologicalSort(this.computePasses);
+    this.renderPassOrder = this.topologicalSort(this.renderPasses);
+
+    this.ready = true;
+  }
+
+  /**
+   * Update game view adapter with latest game update.
+   */
+  updateGameView(gu: GameUpdateViewData): void {
+    if (this.gameViewAdapter) {
+      this.gameViewAdapter.update(gu);
+    }
+  }
+
+  /**
+   * Topological sort of passes based on dependencies.
+   */
+  private topologicalSort<T extends { name: string; dependencies: string[] }>(
+    passes: T[],
+  ): T[] {
+    const passMap = new Map<string, T>();
+    for (const pass of passes) {
+      passMap.set(pass.name, pass);
+    }
+
+    const visited = new Set<string>();
+    const visiting = new Set<string>();
+    const result: T[] = [];
+
+    const visit = (pass: T): void => {
+      if (visiting.has(pass.name)) {
+        console.warn(
+          `Circular dependency detected involving pass: ${pass.name}`,
+        );
+        return;
+      }
+      if (visited.has(pass.name)) {
+        return;
+      }
+
+      visiting.add(pass.name);
+      for (const depName of pass.dependencies) {
+        const dep = passMap.get(depName);
+        if (dep) {
+          visit(dep);
+        }
+      }
+      visiting.delete(pass.name);
+      visited.add(pass.name);
+      result.push(pass);
+    };
+
+    for (const pass of passes) {
+      if (!visited.has(pass.name)) {
+        visit(pass);
+      }
+    }
+
+    return result;
+  }
+
+  setViewSize(width: number, height: number): void {
+    if (!this.resources || !this.device) {
+      return;
+    }
+
+    const nextWidth = Math.max(1, Math.floor(width));
+    const nextHeight = Math.max(1, Math.floor(height));
+
+    // OffscreenCanvas doesn't have width/height properties we can set
+    // The size is managed by the main thread canvas
+    this.resources.setViewSize(nextWidth, nextHeight);
+    this.device.reconfigure();
+
+    if (this.postSmoothingEnabled && this.resources) {
+      this.resources.ensurePostSmoothingTextures(
+        nextWidth,
+        nextHeight,
+        this.device.canvasFormat,
+      );
+      this.resources.invalidateHistory();
+    }
+  }
+
+  setViewTransform(scale: number, offsetX: number, offsetY: number): void {
+    if (!this.resources) {
+      return;
+    }
+    this.resources.setViewTransform(scale, offsetX, offsetY);
+  }
+
+  setAlternativeView(enabled: boolean): void {
+    if (!this.resources) {
+      return;
+    }
+    this.resources.setAlternativeView(enabled);
+  }
+
+  setHighlightedOwnerId(ownerSmallId: number | null): void {
+    if (!this.resources) {
+      return;
+    }
+    this.resources.setHighlightedOwnerId(ownerSmallId);
+  }
+
+  setTerritoryShader(shaderPath: string): void {
+    this.territoryShaderPath = shaderPath;
+    if (this.territoryRenderPass) {
+      void this.territoryRenderPass.setShader(shaderPath);
+    }
+    this.resources?.invalidateHistory();
+  }
+
+  setTerrainShader(shaderPath: string): void {
+    this.terrainShaderPath = shaderPath;
+    if (!this.terrainComputePass) {
+      return;
+    }
+    void this.terrainComputePass.setShader(shaderPath).then(() => {
+      this.refreshTerrain();
+    });
+  }
+
+  setTerritoryShaderParams(
+    params0: Float32Array | number[],
+    params1: Float32Array | number[],
+  ): void {
+    for (let i = 0; i < 4; i++) {
+      this.territoryShaderParams0[i] = Number(params0[i] ?? 0);
+      this.territoryShaderParams1[i] = Number(params1[i] ?? 0);
+    }
+
+    if (!this.resources) {
+      return;
+    }
+    this.resources.setTerritoryShaderParams(
+      this.territoryShaderParams0,
+      this.territoryShaderParams1,
+    );
+    this.resources.invalidateHistory();
+  }
+
+  setTerrainShaderParams(
+    params0: Float32Array | number[],
+    params1: Float32Array | number[],
+  ): void {
+    for (let i = 0; i < 4; i++) {
+      this.terrainShaderParams0[i] = Number(params0[i] ?? 0);
+      this.terrainShaderParams1[i] = Number(params1[i] ?? 0);
+    }
+
+    if (!this.resources) {
+      return;
+    }
+    this.resources.setTerrainShaderParams(
+      this.terrainShaderParams0,
+      this.terrainShaderParams1,
+    );
+    this.refreshTerrain();
+  }
+
+  setPreSmoothing(
+    enabled: boolean,
+    shaderPath: string,
+    params0: Float32Array | number[],
+  ): void {
+    this.preSmoothingEnabled = enabled;
+    if (shaderPath) {
+      this.preSmoothingShaderPath = shaderPath;
+    }
+    for (let i = 0; i < 4; i++) {
+      this.preSmoothingParams0[i] = Number(params0[i] ?? 0);
+    }
+    this.applyPreSmoothingConfig();
+  }
+
+  setPostSmoothing(
+    enabled: boolean,
+    shaderPath: string,
+    params0: Float32Array | number[],
+  ): void {
+    this.postSmoothingEnabled = enabled;
+    if (shaderPath) {
+      this.postSmoothingShaderPath = shaderPath;
+    }
+    for (let i = 0; i < 4; i++) {
+      this.postSmoothingParams0[i] = Number(params0[i] ?? 0);
+    }
+    this.applyPostSmoothingConfig();
+  }
+
+  private applyPreSmoothingConfig(): void {
+    if (!this.resources || !this.visualStateSmoothingPass) {
+      return;
+    }
+
+    this.resources.setUseVisualStateTexture(this.preSmoothingEnabled);
+    if (this.preSmoothingEnabled) {
+      this.resources.ensureVisualStateTexture();
+      void this.visualStateSmoothingPass.setShader(this.preSmoothingShaderPath);
+      this.visualStateSmoothingPass.setParams(this.preSmoothingParams0);
+    } else {
+      this.visualStateSmoothingPass.setParams(new Float32Array(4));
+      this.resources.releaseVisualStateTexture();
+    }
+
+    this.resources.invalidateHistory();
+  }
+
+  private applyPostSmoothingConfig(): void {
+    if (!this.resources || !this.temporalResolvePass || !this.device) {
+      return;
+    }
+
+    if (this.postSmoothingEnabled) {
+      void this.temporalResolvePass.setShader(this.postSmoothingShaderPath);
+      this.temporalResolvePass.setParams(this.postSmoothingParams0);
+      this.temporalResolvePass.setEnabled(true);
+      // Note: canvas size not available here, will be set on first setViewSize
+      if (this.resources) {
+        this.resources.ensurePostSmoothingTextures(
+          1,
+          1,
+          this.device.canvasFormat,
+        );
+      }
+    } else {
+      this.temporalResolvePass.setEnabled(false);
+      this.resources.releasePostSmoothingTextures();
+    }
+
+    this.resources.invalidateHistory();
+  }
+
+  markTile(tile: TileRef): void {
+    if (this.stateUpdatePass) {
+      // TileRef is number, StateUpdatePass.markTile expects number
+      this.stateUpdatePass.markTile(tile as number);
+    }
+  }
+
+  markAllDirty(): void {
+    this.resources?.markDefensePostsDirty();
+  }
+
+  refreshPalette(): void {
+    if (!this.resources) {
+      return;
+    }
+    this.resources.markPaletteDirty();
+  }
+
+  markDefensePostsDirty(): void {
+    if (!this.resources) {
+      return;
+    }
+    this.resources.markDefensePostsDirty();
+  }
+
+  refreshTerrain(): void {
+    if (!this.resources || !this.device) {
+      return;
+    }
+    this.resources.markTerrainParamsDirty();
+    if (this.terrainComputePass) {
+      this.terrainComputePass.markDirty();
+      this.computeTerrainImmediate();
+    }
+  }
+
+  private computeTerrainImmediate(): void {
+    if (
+      !this.ready ||
+      !this.device ||
+      !this.resources ||
+      !this.terrainComputePass
+    ) {
+      return;
+    }
+
+    this.resources.uploadTerrainParams();
+
+    if (!this.terrainComputePass.needsUpdate()) {
+      return;
+    }
+
+    const encoder = this.device.device.createCommandEncoder();
+    this.terrainComputePass.execute(encoder, this.resources);
+    this.device.device.queue.submit([encoder.finish()]);
+
+    if (this.territoryRenderPass) {
+      (this.territoryRenderPass as any).rebuildBindGroup?.();
+    }
+  }
+
+  /**
+   * Perform one simulation tick.
+   * Runs compute passes to update ground truth data.
+   */
+  tick(): void {
+    if (!this.ready || !this.device || !this.resources) {
+      return;
+    }
+
+    this.resources.updateTickTiming(performance.now() / 1000);
+
+    if (
+      this.gameViewAdapter?.config().defensePostRange() !==
+      this.defensePostRange
+    ) {
+      throw new Error("defensePostRange changed at runtime; unsupported.");
+    }
+
+    // Upload palette if needed
+    this.resources.uploadPalette();
+
+    // Upload diplomacy relations
+    this.resources.uploadRelations();
+
+    // Upload defense posts if needed
+    this.resources.uploadDefensePosts();
+
+    // Initial state upload
+    this.resources.uploadState();
+
+    const stateUpdatesPending = this.stateUpdatePass?.needsUpdate() ?? false;
+    if (!stateUpdatesPending) {
+      this.resources.setLastStateUpdateCount(0);
+    }
+
+    const needsCompute =
+      (this.terrainComputePass?.needsUpdate() ?? false) ||
+      stateUpdatesPending ||
+      (this.defendedStrengthFullPass?.needsUpdate() ?? false) ||
+      (this.defendedStrengthPass?.needsUpdate() ?? false);
+
+    if (!needsCompute) {
+      return;
+    }
+
+    const encoder = this.device.device.createCommandEncoder();
+
+    if (this.preSmoothingEnabled && stateUpdatesPending) {
+      this.resources.ensureVisualStateTexture();
+      const visualStateTexture = this.resources.getVisualStateTexture();
+      if (visualStateTexture) {
+        encoder.copyTextureToTexture(
+          { texture: this.resources.stateTexture },
+          { texture: visualStateTexture },
+          {
+            width: this.resources.getMapWidth(),
+            height: this.resources.getMapHeight(),
+            depthOrArrayLayers: 1,
+          },
+        );
+        this.resources.consumeVisualStateSyncNeeded();
+      }
+    }
+
+    // Execute compute passes in dependency order
+    for (const pass of this.computePassOrder) {
+      if (!pass.needsUpdate()) {
+        continue;
+      }
+      pass.execute(encoder, this.resources);
+    }
+
+    this.device.device.queue.submit([encoder.finish()]);
+  }
+
+  /**
+   * Render one frame.
+   * Runs render passes to draw to the canvas.
+   */
+  render(): void {
+    if (
+      !this.ready ||
+      !this.device ||
+      !this.resources ||
+      !this.territoryRenderPass
+    ) {
+      return;
+    }
+
+    const nowSec = performance.now() / 1000;
+    this.resources.writeTemporalUniformBuffer(nowSec);
+
+    // If terrain needs recomputation, trigger it asynchronously
+    if (this.terrainComputePass?.needsUpdate()) {
+      this.resources.uploadTerrainParams();
+      const computeEncoder = this.device.device.createCommandEncoder();
+      this.terrainComputePass.execute(computeEncoder, this.resources);
+      this.device.device.queue.submit([computeEncoder.finish()]);
+    }
+
+    const encoder = this.device.device.createCommandEncoder();
+    const swapchainView = this.device.context.getCurrentTexture().createView();
+
+    if (
+      this.preSmoothingEnabled &&
+      this.resources.consumeVisualStateSyncNeeded()
+    ) {
+      const visualStateTexture = this.resources.getVisualStateTexture();
+      if (visualStateTexture) {
+        encoder.copyTextureToTexture(
+          { texture: this.resources.stateTexture },
+          { texture: visualStateTexture },
+          {
+            width: this.resources.getMapWidth(),
+            height: this.resources.getMapHeight(),
+            depthOrArrayLayers: 1,
+          },
+        );
+      }
+    }
+
+    for (const pass of this.frameComputePasses) {
+      if (!pass.needsUpdate()) {
+        continue;
+      }
+      pass.execute(encoder, this.resources);
+    }
+
+    // Execute render passes in dependency order
+    for (const pass of this.renderPassOrder) {
+      if (!pass.needsUpdate()) {
+        continue;
+      }
+      if (pass === this.territoryRenderPass && this.postSmoothingEnabled) {
+        if (!this.resources.getCurrentColorTexture()) {
+          // Use view size from resources (stored via setViewSize)
+          const viewWidth = (this.resources as any).viewWidth ?? 1;
+          const viewHeight = (this.resources as any).viewHeight ?? 1;
+          this.resources.ensurePostSmoothingTextures(
+            viewWidth,
+            viewHeight,
+            this.device.canvasFormat,
+          );
+        }
+        const currentTexture = this.resources.getCurrentColorTexture();
+        if (currentTexture) {
+          pass.execute(encoder, this.resources, currentTexture.createView());
+        }
+        continue;
+      }
+
+      pass.execute(encoder, this.resources, swapchainView);
+    }
+
+    this.device.device.queue.submit([encoder.finish()]);
+  }
+}