diff --git a/apps/desktop/src/components/MessageBubble.tsx b/apps/desktop/src/components/MessageBubble.tsx
index 15e5174..0b1eee9 100644
--- a/apps/desktop/src/components/MessageBubble.tsx
+++ b/apps/desktop/src/components/MessageBubble.tsx
@@ -442,6 +442,32 @@ export function MessageBubble({
                   defaultValue: 'Nachricht nicht lesbar',
                 })}
               </span>
+            ) : parsed.kind === 'game' ? (
+              <div className="flex items-center gap-3 rounded-2xl border border-accent/30 bg-accent/5 px-4 py-3">
+                <div className="flex h-10 w-10 shrink-0 items-center justify-center rounded-lg bg-accent/20 text-accent">
+                  <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth={2}
+                       strokeLinecap="round" strokeLinejoin="round" className="h-5 w-5">
+                    <rect x="3" y="6" width="18" height="12" rx="3" />
+                    <path d="M8 12h4M10 10v4M16 11v.01M16 14v.01" />
+                  </svg>
+                </div>
+                <div className="min-w-0 flex-1">
+                  <div className="text-sm font-semibold text-fg">{parsed.gameType === 'c4' ? 'Vier-Gewinnt' : 'Tic-Tac-Toe'}</div>
+                  <div className="text-xs text-fg-muted">Gemeinsam spielen</div>
+                </div>
+                <button
+                  type="button"
+                  onClick={() => {
+                    window.dispatchEvent(
+                      new CustomEvent('chatapp:open-game', { detail: { id: parsed.gameId } }),
+                    );
+                  }}
+                  disabled={!parsed.gameId}
+                  className="cursor-pointer rounded-md bg-accent px-3 py-1.5 text-xs font-semibold text-accent-fg transition hover:bg-accent/90 disabled:cursor-not-allowed disabled:opacity-50"
+                >
+                  Spielen
+                </button>
+              </div>
             ) : parsed.kind === 'watch_together' ? (
               <div className="flex items-center gap-3 rounded-2xl border border-accent/30 bg-accent/5 px-4 py-3">
                 <div className="flex h-10 w-10 shrink-0 items-center justify-center rounded-lg bg-accent/20 text-accent">
diff --git a/apps/desktop/src/lib/conversationFeatures.ts b/apps/desktop/src/lib/conversationFeatures.ts
index 4fd2ed1..bc1f023 100644
--- a/apps/desktop/src/lib/conversationFeatures.ts
+++ b/apps/desktop/src/lib/conversationFeatures.ts
@@ -6,6 +6,7 @@ import {
   type PollOption,
   type WhiteboardPayload,
   type WatchTogetherPayload,
+  type GamePayload,
 } from '@chat-app/shared/chat';
 
 export type AttachmentBucket = 'media' | 'audio' | 'files';
@@ -117,6 +118,16 @@ export function createWatchTogetherPayload(sessionId: string): string {
   return serializeMessagePayload(payload);
 }
 
+export function createGamePayload(gameId: string, gameType: 'ttt' | 'c4'): string {
+  const payload: GamePayload = {
+    v: 1,
+    type: 'game',
+    game_id: gameId,
+    game_type: gameType,
+  };
+  return serializeMessagePayload(payload);
+}
+
 export function summarizePollVotes(
   options: PollOption[],
   reactions: ReactionSummaryInput[],
diff --git a/apps/desktop/src/pages/ConversationPage.tsx b/apps/desktop/src/pages/ConversationPage.tsx
index 03062a6..214a014 100644
--- a/apps/desktop/src/pages/ConversationPage.tsx
+++ b/apps/desktop/src/pages/ConversationPage.tsx
@@ -47,10 +47,12 @@ import {
   createPollPayload,
   createWhiteboardPayload,
   createWatchTogetherPayload,
+  createGamePayload,
 } from '../lib/conversationFeatures';
 import { WhiteboardModal } from '../components/WhiteboardModal';
 import { WatchTogetherModal } from '../components/WatchTogetherModal';
-import { createWhiteboard, createWatchSession, parseYouTubeUrl } from '@chat-app/shared/chat';
+import { GameModal } from '../components/GameModal';
+import { createWhiteboard, createWatchSession, parseYouTubeUrl, createGame, type GameType } from '@chat-app/shared/chat';
 import { compressImages } from '../lib/imageCompress';
 import { ensureInstallId } from '../lib/installId';
 import { searchCachedMessages } from '../lib/messageCache';
@@ -176,6 +178,10 @@ export function ConversationPage() {
   const [watchUrl, setWatchUrl] = useState('');
   const [watchError, setWatchError] = useState<string | null>(null);
   const [watchCreating, setWatchCreating] = useState(false);
+  const [openGameId, setOpenGameId] = useState<string | null>(null);
+  const [gameDialogOpen, setGameDialogOpen] = useState(false);
+  const [gameError, setGameError] = useState<string | null>(null);
+  const [gameCreating, setGameCreating] = useState(false);
   const [pollError, setPollError] = useState<string | null>(null);
   const [replyTo, setReplyTo] = useState<DecryptedMessage | null>(null);
   const [forwardTarget, setForwardTarget] = useState<DecryptedMessage | null>(null);
@@ -488,6 +494,15 @@ export function ConversationPage() {
     return () => window.removeEventListener('chatapp:open-watch-together', onOpen);
   }, []);
 
+  useEffect(() => {
+    const onOpen = (e: Event) => {
+      const detail = (e as CustomEvent<{ id?: string }>).detail;
+      if (detail?.id) setOpenGameId(detail.id);
+    };
+    window.addEventListener('chatapp:open-game', onOpen);
+    return () => window.removeEventListener('chatapp:open-game', onOpen);
+  }, []);
+
   useEffect(() => {
     if (id && messages.length > 0) markRead(id);
   }, [id, messages.length, markRead]);
@@ -663,6 +678,38 @@ export function ConversationPage() {
     }
   }, [id, watchUrl, send, replyTo?.id]);
 
+  const handleStartGame = useCallback(async (gameType: GameType) => {
+    if (!id) return;
+    if (!conversation || conversation.members.length !== 2) {
+      setGameError('Spiele aktuell nur in 1:1-Chats.');
+      return;
+    }
+    const opponent = conversation.members.find((m) => m.userId !== myId);
+    if (!opponent) {
+      setGameError('Kein Gegner gefunden.');
+      return;
+    }
+    setGameCreating(true);
+    setGameError(null);
+    try {
+      const game = await createGame(supabase, {
+        conversationId: id,
+        gameType,
+        opponentUserId: opponent.userId,
+      });
+      const payload = createGamePayload(game.id, gameType);
+      await send(payload, [], replyTo?.id ?? null);
+      setReplyTo(null);
+      setStickToBottom(true);
+      setGameDialogOpen(false);
+      setOpenGameId(game.id);
+    } catch (err: unknown) {
+      setGameError(err instanceof Error ? err.message : 'Konnte Spiel nicht starten');
+    } finally {
+      setGameCreating(false);
+    }
+  }, [id, conversation, myId, send, replyTo?.id]);
+
   async function ingestFiles(files: File[]) {
     const compressed = await compressImages(files);
     const next: File[] = [];
@@ -1075,6 +1122,15 @@ export function ConversationPage() {
           >
             <PlayBoxIcon className="h-4 w-4" />
           </button>
+          <button
+            type="button"
+            onClick={() => setGameDialogOpen(true)}
+            title={t('app:composer.game', { defaultValue: 'Spielen' })}
+            aria-label={t('app:composer.game', { defaultValue: 'Spielen' })}
+            className="flex h-9 w-9 cursor-pointer items-center justify-center rounded-md text-fg-muted transition hover:bg-surface-3 hover:text-fg"
+          >
+            <GameIcon className="h-4 w-4" />
+          </button>
           <div className="relative">
             <button
               type="button"
@@ -1289,6 +1345,62 @@ export function ConversationPage() {
         />
       )}
 
+      {openGameId && (
+        <GameModal
+          gameId={openGameId}
+          onClose={() => setOpenGameId(null)}
+        />
+      )}
+
+      {gameDialogOpen && (
+        <div
+          role="dialog"
+          aria-modal="true"
+          className="fixed inset-0 z-[70] flex items-center justify-center bg-ink-950/90 p-6"
+          onClick={(e) => {
+            if (e.target === e.currentTarget) setGameDialogOpen(false);
+          }}
+        >
+          <div className="w-full max-w-sm rounded-2xl border border-line bg-surface-2 p-5 shadow-xl">
+            <h2 className="mb-3 font-display text-lg font-semibold text-fg">
+              {t('app:game.pick_title', { defaultValue: 'Spiel auswählen' })}
+            </h2>
+            {gameError && (
+              <p className="mb-2 text-xs text-rose-400">{gameError}</p>
+            )}
+            <div className="grid grid-cols-2 gap-3">
+              <button
+                type="button"
+                onClick={() => void handleStartGame('ttt')}
+                disabled={gameCreating}
+                className="flex flex-col items-center gap-2 rounded-xl border border-line bg-surface-3 p-4 text-fg transition hover:border-accent/40 hover:bg-surface disabled:cursor-not-allowed disabled:opacity-50"
+              >
+                <span className="text-3xl">×○</span>
+                <span className="text-xs font-semibold">Tic-Tac-Toe</span>
+              </button>
+              <button
+                type="button"
+                onClick={() => void handleStartGame('c4')}
+                disabled={gameCreating}
+                className="flex flex-col items-center gap-2 rounded-xl border border-line bg-surface-3 p-4 text-fg transition hover:border-accent/40 hover:bg-surface disabled:cursor-not-allowed disabled:opacity-50"
+              >
+                <span className="text-3xl">🔴🟡</span>
+                <span className="text-xs font-semibold">Vier-Gewinnt</span>
+              </button>
+            </div>
+            <div className="mt-4 flex justify-end">
+              <button
+                type="button"
+                onClick={() => { setGameDialogOpen(false); setGameError(null); }}
+                className="cursor-pointer rounded-md border border-line bg-surface-3 px-3 py-1.5 text-xs font-medium text-fg-muted transition hover:bg-surface"
+              >
+                {t('app:game.cancel', { defaultValue: 'Abbrechen' })}
+              </button>
+            </div>
+          </div>
+        </div>
+      )}
+
       {watchDialogOpen && (
         <div
           role="dialog"
@@ -1633,3 +1745,13 @@ function PlayBoxIcon(props: React.SVGProps<SVGSVGElement>) {
     </svg>
   );
 }
+
+function GameIcon(props: React.SVGProps<SVGSVGElement>) {
+  return (
+    <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth={2}
+         strokeLinecap="round" strokeLinejoin="round" {...props}>
+      <rect x="3" y="6" width="18" height="12" rx="3" />
+      <path d="M8 12h4M10 10v4M16 11v.01M16 14v.01" />
+    </svg>
+  );
+}