diff --git a/client/src/components/TetrisGame.tsx b/client/src/components/TetrisGame.tsx
index f6b617c..41b8061 100644
--- a/client/src/components/TetrisGame.tsx
+++ b/client/src/components/TetrisGame.tsx
@@ -431,6 +431,8 @@ export default function TetrisGame() {
                         <ul className="tetris-players">
                             {state?.players.map(p => <li key={p.login}>{p.login}{p.login === state.host && ' 👑'}</li>)}
                         </ul>
+                        {state && state.players.length < state.minPlayers &&
+                            <p className="text-muted">Čeká se na další hráče… Pro hru o samotě použijte Trénink.</p>}
                         {renderSettings()}
                     </>
                 );
@@ -503,7 +505,7 @@ export default function TetrisGame() {
             </Button>);
             if (login === state?.host) {
                 buttons.push(<Button key="start" onClick={() => send('tetris:start')}
-                    disabled={(state?.players.length ?? 0) < (state?.minPlayers ?? 1)}>Spustit hru</Button>);
+                    disabled={(state?.players.length ?? 0) < (state?.minPlayers ?? 2)}>Spustit hru</Button>);
             }
         }
         buttons.push(<Button key="close" variant="secondary" onClick={() => setOpen(false)}>Zavřít</Button>);
diff --git a/server/src/tests/tetrisGame.test.ts b/server/src/tests/tetrisGame.test.ts
index 8745c7d..934e032 100644
--- a/server/src/tests/tetrisGame.test.ts
+++ b/server/src/tests/tetrisGame.test.ts
@@ -4,12 +4,12 @@ import { fakeClock } from './helpers/fakeClock';
 
 const BOARD = '0'.repeat(BOARD_WIDTH * (BOARD_HEIGHT - 1)) + '1'.repeat(BOARD_WIDTH);
 
-function setup() {
+function setup(minPlayers = 1) {
     const clock = fakeClock();
     const all: TetrisState[] = [];
     const watched: TetrisState[] = [];
     const garbage: GarbageEvent[] = [];
-    const game = new TetrisGame(s => all.push(s), s => watched.push(s), e => garbage.push(e), 1, clock);
+    const game = new TetrisGame(s => all.push(s), s => watched.push(s), e => garbage.push(e), minPlayers, clock);
     const last = () => all[all.length - 1];
     const startWith = (settings: Partial<TetrisSettings>, ...logins: string[]) => {
         logins.forEach(l => game.join(l));
@@ -22,6 +22,16 @@ function setup() {
 }
 
 describe('tetris', () => {
+    test('společnou hru nejde spustit jen s jedním hráčem', () => {
+        const ctx = setup(2);
+        ctx.game.join('alice');
+        expect(() => ctx.game.start('alice')).toThrow(GameError);
+        expect(ctx.last()).toMatchObject({ phase: 'lobby' });
+        ctx.game.join('bob');
+        ctx.game.start('alice');
+        expect(ctx.last()).toMatchObject({ phase: 'countdown' });
+    });
+
     test('po odpočtu začne hra se společným seedem', () => {
         const ctx = setup();
         ctx.startGame('alice', 'bob');
diff --git a/server/src/tetrisGame.ts b/server/src/tetrisGame.ts
index 4b8e23f..2d8f1fb 100644
--- a/server/src/tetrisGame.ts
+++ b/server/src/tetrisGame.ts
@@ -1,5 +1,5 @@
 import { Server } from "socket.io";
-import { Clock, defaultClock, GameError, gameHandler } from "./minigames";
+import { Clock, defaultClock, GameError, gameHandler, minPlayersForEnv } from "./minigames";
 
 /**
  * Multiplayerový Tetris (battle) přes websocket.
@@ -124,7 +124,7 @@ export class TetrisGame {
         private readonly broadcastAll: (state: TetrisState) => void,
         private readonly broadcastWatchers: (state: TetrisState) => void,
         private readonly sendGarbage: (event: GarbageEvent) => void,
-        private readonly minPlayers = 1,
+        private readonly minPlayers = 2,
         private readonly clock: Clock = defaultClock,
     ) { }
 
@@ -366,7 +366,8 @@ export function registerTetrisGame(io: Server) {
         state => io.emit('tetris:state', state),
         state => io.to(WATCH_ROOM).emit('tetris:state', state),
         event => io.to(WATCH_ROOM).emit('tetris:garbage', event),
-        1, // Tetris se dá hrát i sólo
+        // Sólo hra je jen Trénink v prohlížeči, společná hra by blokovala ostatní
+        minPlayersForEnv(2),
     );
 
     io.on('connection', socket => {