diff --git a/src/components/game/BattleSimulatorPanel.tsx b/src/components/game/BattleSimulatorPanel.tsx
index 7eafd139..2b000e8e 100644
--- a/src/components/game/BattleSimulatorPanel.tsx
+++ b/src/components/game/BattleSimulatorPanel.tsx
@@ -223,6 +223,12 @@ export const BattleSimulatorPanel = memo(function BattleSimulatorPanel() {
       return;
     }
 
+    // Register both players as AI-controlled so the AI takes over and fights
+    const player1Faction = playerSlots[0]?.faction ?? 'dominion';
+    const player2Faction = playerSlots[1]?.faction ?? 'dominion';
+    bridge.registerAI('player1', player1Faction, 'medium');
+    bridge.registerAI('player2', player2Faction, 'medium');
+
     const currentTick = bridge.currentTick;
 
     // Get all units from render state adapter
@@ -278,7 +284,7 @@ export const BattleSimulatorPanel = memo(function BattleSimulatorPanel() {
     bridge.resume();
     setIsPaused(false);
     setSelectedUnit(null);
-  }, []);
+  }, [playerSlots]);
 
   const handlePauseToggle = useCallback(() => {
     const bridge = getWorkerBridge();
diff --git a/src/components/game/hooks/useWorkerBridge.ts b/src/components/game/hooks/useWorkerBridge.ts
index f2fc9206..7d2bf4ab 100644
--- a/src/components/game/hooks/useWorkerBridge.ts
+++ b/src/components/game/hooks/useWorkerBridge.ts
@@ -20,7 +20,12 @@ import {
   type RenderState,
   type GameEvent,
 } from '@/engine/workers';
-import { useGameSetupStore, getLocalPlayerId, isBattleSimulatorMode, type GameSetupState } from '@/store/gameSetupStore';
+import {
+  useGameSetupStore,
+  getLocalPlayerId,
+  isBattleSimulatorMode,
+  type GameSetupState,
+} from '@/store/gameSetupStore';
 import { useUIStore } from '@/store/uiStore';
 import { useGameStore } from '@/store/gameStore';
 import { isMultiplayerMode } from '@/store/multiplayerStore';
@@ -158,7 +163,7 @@ export function useWorkerBridge({ map, onGameOver }: UseWorkerBridgeProps): UseW
           tickRate: 20,
           isMultiplayer,
           playerId: localPlayerId ?? 'spectator',
-          aiEnabled: !isBattleSimulatorMode() && !isMultiplayer,
+          aiEnabled: !isMultiplayer,
           aiDifficulty: 'medium',
           fogOfWar,
         },
diff --git a/src/engine/workers/GameWorker.ts b/src/engine/workers/GameWorker.ts
index 4492cae5..db23b4f1 100644
--- a/src/engine/workers/GameWorker.ts
+++ b/src/engine/workers/GameWorker.ts
@@ -655,6 +655,14 @@ export class WorkerGame extends GameCore {
     return this.gameTime;
   }
 
+  /**
+   * Force send a render state update to the main thread.
+   * Used when entities are spawned/destroyed while the game is paused.
+   */
+  public forceRenderStateUpdate(): void {
+    this.sendRenderState();
+  }
+
   // ============================================================================
   // RENDER STATE COLLECTION
   // ============================================================================
@@ -1417,12 +1425,29 @@ if (typeof self !== 'undefined') {
             y: message.y,
             playerId: message.playerId,
           });
+          // Send render state so main thread sees the new entity (even when paused)
+          game.forceRenderStateUpdate();
           break;
         }
 
         case 'destroyEntity': {
           if (!game) return;
           game.eventBus.emit('entity:destroy', { entityId: message.entityId });
+          // Send render state so main thread sees the entity removal (even when paused)
+          game.forceRenderStateUpdate();
+          break;
+        }
+
+        case 'registerAI': {
+          if (!game) return;
+          const enhancedAI = game.world.getSystem(EnhancedAISystem);
+          if (enhancedAI) {
+            enhancedAI.registerAI(
+              message.playerId,
+              message.faction,
+              message.difficulty ?? 'medium'
+            );
+          }
           break;
         }
       }
diff --git a/src/engine/workers/WorkerBridge.ts b/src/engine/workers/WorkerBridge.ts
index fe2acdb6..0e6d4331 100644
--- a/src/engine/workers/WorkerBridge.ts
+++ b/src/engine/workers/WorkerBridge.ts
@@ -561,6 +561,22 @@ export class WorkerBridge {
     } satisfies MainToWorkerMessage);
   }
 
+  /**
+   * Register a player as AI-controlled (for battle simulator)
+   */
+  public registerAI(
+    playerId: string,
+    faction: string,
+    difficulty: 'easy' | 'medium' | 'hard' | 'insane' = 'medium'
+  ): void {
+    this.worker?.postMessage({
+      type: 'registerAI',
+      playerId,
+      faction,
+      difficulty,
+    } satisfies MainToWorkerMessage);
+  }
+
   public setControlGroup(groupNumber: number, entityIds: number[]): void {
     this.worker?.postMessage({
       type: 'setControlGroup',
diff --git a/src/engine/workers/types.ts b/src/engine/workers/types.ts
index bf76e90f..5789e7ea 100644
--- a/src/engine/workers/types.ts
+++ b/src/engine/workers/types.ts
@@ -358,7 +358,12 @@ export interface SelectionChangedEvent {
 
 export interface AlertEvent {
   type: 'alert';
-  alertType: 'under_attack' | 'unit_ready' | 'research_complete' | 'resources_low' | 'base_destroyed';
+  alertType:
+    | 'under_attack'
+    | 'unit_ready'
+    | 'research_complete'
+    | 'resources_low'
+    | 'base_destroyed';
   position?: { x: number; y: number };
   playerId: string;
   details?: string;
@@ -418,7 +423,13 @@ export type MainToWorkerMessage =
   | { type: 'spawnEntities'; mapData: SpawnMapData }
   | { type: 'setPerformanceCollection'; enabled: boolean }
   | { type: 'spawnUnit'; unitType: string; x: number; y: number; playerId: string }
-  | { type: 'destroyEntity'; entityId: number };
+  | { type: 'destroyEntity'; entityId: number }
+  | {
+      type: 'registerAI';
+      playerId: string;
+      faction: string;
+      difficulty?: 'easy' | 'medium' | 'hard' | 'insane';
+    };
 
 /**
  * Player slot info for spawning
@@ -503,7 +514,21 @@ export type { GameCommand } from '../core/GameCommand';
  */
 export const TRANSFORM_FLOATS_PER_ENTITY = 11;
 
-export function packTransforms(entities: Array<{ x: number; y: number; z: number; rotation: number; scaleX: number; scaleY: number; scaleZ: number; prevX: number; prevY: number; prevZ: number; prevRotation: number }>): Float32Array {
+export function packTransforms(
+  entities: Array<{
+    x: number;
+    y: number;
+    z: number;
+    rotation: number;
+    scaleX: number;
+    scaleY: number;
+    scaleZ: number;
+    prevX: number;
+    prevY: number;
+    prevZ: number;
+    prevRotation: number;
+  }>
+): Float32Array {
   const buffer = new Float32Array(entities.length * TRANSFORM_FLOATS_PER_ENTITY);
   let offset = 0;
   for (const e of entities) {
@@ -522,10 +547,21 @@ export function packTransforms(entities: Array<{ x: number; y: number; z: number
   return buffer;
 }
 
-export function unpackTransform(buffer: Float32Array, index: number): {
-  x: number; y: number; z: number; rotation: number;
-  scaleX: number; scaleY: number; scaleZ: number;
-  prevX: number; prevY: number; prevZ: number; prevRotation: number;
+export function unpackTransform(
+  buffer: Float32Array,
+  index: number
+): {
+  x: number;
+  y: number;
+  z: number;
+  rotation: number;
+  scaleX: number;
+  scaleY: number;
+  scaleZ: number;
+  prevX: number;
+  prevY: number;
+  prevZ: number;
+  prevRotation: number;
 } {
   const offset = index * TRANSFORM_FLOATS_PER_ENTITY;
   return {