diff --git a/README.md b/README.md
index ad91a9b0..56f63fc0 100644
--- a/README.md
+++ b/README.md
@@ -55,7 +55,7 @@ Connection made    → Direct peer-to-peer, Nostr disconnected
 
 If Nostr becomes unavailable, players can fall back to manual connection code exchange. The game continues to function regardless of external infrastructure.
 
-**Implementation:** `src/engine/network/p2p/NostrMatchmaking.ts`, `ConnectionCode.ts`
+**Implementation:** `src/hooks/useMultiplayer.ts`, `src/store/multiplayerStore.ts`
 
 ---
 
diff --git a/src/components/game/WebGPUGameCanvas.tsx b/src/components/game/WebGPUGameCanvas.tsx
index d7b8c878..5ea1aec1 100644
--- a/src/components/game/WebGPUGameCanvas.tsx
+++ b/src/components/game/WebGPUGameCanvas.tsx
@@ -147,7 +147,6 @@ export function WebGPUGameCanvas() {
     eventBusRef,
     isGameInitialized: isWorkerInitialized,
     placementPreviewRef: refs.placementPreview,
-    wallPlacementPreviewRef: refs.wallPlacementPreview,
     overlayManagerRef: refs.overlayManager,
     lastControlGroupTap,
   });
@@ -160,7 +159,6 @@ export function WebGPUGameCanvas() {
     cameraRef: refs.camera,
     environmentRef: refs.environment,
     lightPoolRef: refs.lightPool,
-    fogOfWarRef: refs.fogOfWar,
     containerRef,
     map: CURRENT_MAP,
   });
diff --git a/src/components/game/hooks/useGameInput.ts b/src/components/game/hooks/useGameInput.ts
index 275056b5..0b040e05 100644
--- a/src/components/game/hooks/useGameInput.ts
+++ b/src/components/game/hooks/useGameInput.ts
@@ -18,7 +18,6 @@ import type { IWorldProvider } from '@/engine/ecs/IWorldProvider';
 import type { EventBus } from '@/engine/core/EventBus';
 import { RTSCamera } from '@/rendering/Camera';
 import { BuildingPlacementPreview } from '@/rendering/BuildingPlacementPreview';
-import { WallPlacementPreview } from '@/rendering/WallPlacementPreview';
 import { TSLGameOverlayManager } from '@/rendering/tsl';
 import { getLocalPlayerId } from '@/store/gameSetupStore';
 import {
@@ -44,8 +43,6 @@ export interface UseGameInputProps {
   /** Signal that game is initialized - triggers InputManager dependency update */
   isGameInitialized?: boolean;
   placementPreviewRef: MutableRefObject<BuildingPlacementPreview | null>;
-  /** @deprecated No longer used - wall placement handled by BuildingInputHandler */
-  wallPlacementPreviewRef?: MutableRefObject<WallPlacementPreview | null>;
   overlayManagerRef: MutableRefObject<TSLGameOverlayManager | null>;
   lastControlGroupTap: MutableRefObject<{ group: number; time: number } | null>;
 }
diff --git a/src/components/game/hooks/usePostProcessing.ts b/src/components/game/hooks/usePostProcessing.ts
index 1cd663bb..ba721b56 100644
--- a/src/components/game/hooks/usePostProcessing.ts
+++ b/src/components/game/hooks/usePostProcessing.ts
@@ -8,7 +8,7 @@
 import type { MutableRefObject, RefObject } from 'react';
 import { useEffect, useRef } from 'react';
 import * as THREE from 'three';
-import { RenderContext, RenderPipeline, TSLFogOfWar } from '@/rendering/tsl';
+import { RenderContext, RenderPipeline } from '@/rendering/tsl';
 import { EnvironmentManager } from '@/rendering/EnvironmentManager';
 import { LightPool } from '@/rendering/LightPool';
 import { RTSCamera } from '@/rendering/Camera';
@@ -24,8 +24,6 @@ export interface UsePostProcessingProps {
   cameraRef: MutableRefObject<RTSCamera | null>;
   environmentRef: MutableRefObject<EnvironmentManager | null>;
   lightPoolRef: MutableRefObject<LightPool | null>;
-  /** @deprecated Fog of war is now handled via RenderPipeline */
-  fogOfWarRef?: MutableRefObject<TSLFogOfWar | null>;
   containerRef: RefObject<HTMLDivElement | null>;
   map: MapData;
 }
@@ -37,7 +35,6 @@ export function usePostProcessing({
   cameraRef,
   environmentRef,
   lightPoolRef,
-  fogOfWarRef: _fogOfWarRef,
   containerRef,
   map,
 }: UsePostProcessingProps): void {
diff --git a/src/engine/core/Game.ts b/src/engine/core/Game.ts
index 28aea3f4..f531c17e 100644
--- a/src/engine/core/Game.ts
+++ b/src/engine/core/Game.ts
@@ -24,7 +24,6 @@ import {
   getDesyncState,
   useMultiplayerStore,
   getAdaptiveCommandDelay,
-  getSlotIdForPeer,
   getAllRemoteSlotIds,
   setOnReconnectedCallback,
 } from '@/store/multiplayerStore';
@@ -180,22 +179,17 @@ export class Game extends GameCore {
           // Commands use slot IDs (e.g., "player1", "player2"), not peer IDs
           const validRemoteSlotIds = getAllRemoteSlotIds();
           if (!validRemoteSlotIds.includes(command.playerId)) {
-            // Also check legacy single-peer mode
-            const legacyPeerId = useMultiplayerStore.getState().remotePeerId;
-            const legacySlotId = legacyPeerId ? getSlotIdForPeer(legacyPeerId) : null;
-            if (command.playerId !== legacySlotId) {
-              console.error(
-                `[Game] SECURITY: Rejected command with invalid playerId. ` +
-                  `Valid slot IDs: [${validRemoteSlotIds.join(', ')}], Got: ${command.playerId}`
-              );
-              this.eventBus.emit('security:spoofedPlayerId', {
-                expectedPlayerId: validRemoteSlotIds.join(', '),
-                spoofedPlayerId: command.playerId,
-                commandType: command.type,
-                tick: command.tick,
-              });
-              return;
-            }
+            console.error(
+              `[Game] SECURITY: Rejected command with invalid playerId. ` +
+                `Valid slot IDs: [${validRemoteSlotIds.join(', ')}], Got: ${command.playerId}`
+            );
+            this.eventBus.emit('security:spoofedPlayerId', {
+              expectedPlayerId: validRemoteSlotIds.join(', '),
+              spoofedPlayerId: command.playerId,
+              commandType: command.type,
+              tick: command.tick,
+            });
+            return;
           }
 
           // SECURITY: Validate command tick is within acceptable range
@@ -611,17 +605,6 @@ export class Game extends GameCore {
       }
     }
 
-    // Fallback for legacy single-peer mode: try to get slot ID from peer ID mapping
-    if (remoteSlotIds.length === 0) {
-      const remotePeerId = useMultiplayerStore.getState().remotePeerId;
-      if (remotePeerId) {
-        const slotId = getSlotIdForPeer(remotePeerId);
-        if (slotId && !players.includes(slotId)) {
-          players.push(slotId);
-        }
-      }
-    }
-
     return players;
   }
 
diff --git a/src/hooks/useLobbySync.ts b/src/hooks/useLobbySync.ts
index e826a0e0..90d6593e 100644
--- a/src/hooks/useLobbySync.ts
+++ b/src/hooks/useLobbySync.ts
@@ -114,7 +114,6 @@ export function useLobbySync({ playerName, isPublicLobby }: UseLobbyOptions): Lo
     setMultiplayer,
     setConnected,
     setHost,
-    setDataChannel,
   } = useMultiplayerStore();
 
   // Derived state
@@ -124,27 +123,24 @@ export function useLobbySync({ playerName, isPublicLobby }: UseLobbyOptions): Lo
   const isGuestMode = lobbyStatus === 'connected' && !isHost;
 
   // When connected as guest, set up multiplayer store
+  // Note: Data channel is set up via addPeer() in useMultiplayer.ts
   useEffect(() => {
     if (lobbyStatus === 'connected' && hostConnection) {
       setMultiplayer(true);
       setConnected(true);
       setHost(false);
-      setDataChannel(hostConnection);
     }
-  }, [lobbyStatus, hostConnection, setMultiplayer, setConnected, setHost, setDataChannel]);
+  }, [lobbyStatus, hostConnection, setMultiplayer, setConnected, setHost]);
 
   // When hosting with connected guests, set up multiplayer
+  // Note: Data channels are set up via addPeer() in useMultiplayer.ts
   useEffect(() => {
     if (isHost && guests.some(g => g.dataChannel)) {
       setMultiplayer(true);
       setConnected(true);
       setHost(true);
-      const firstConnectedGuest = guests.find(g => g.dataChannel);
-      if (firstConnectedGuest?.dataChannel) {
-        setDataChannel(firstConnectedGuest.dataChannel);
-      }
     }
-  }, [isHost, guests, setMultiplayer, setConnected, setHost, setDataChannel]);
+  }, [isHost, guests, setMultiplayer, setConnected, setHost]);
 
   // Send lobby state to guests whenever it changes (host only)
   useEffect(() => {