Undo Chess: chess with take-back tokens

The rules

1. Before the game, choose how many take-back tokens each player gets: 0, 1, 2 or 3. The default is 2 each — 4 tokens in the game.
2. On your turn you can give one of your tokens to your opponent and take a move back: your opponent’s last move and your own move before it are cancelled. The board returns to the position before your move, and you move again.
3. Tokens never vanish and never appear from nowhere — they only change hands. The total at the start stays the same until the end of the game.
4. Time is not given back: the clocks carry on from where they were.
5. Your opponent’s consent is not needed: the token is yours, and you spend it when you decide. You can take back several moves in a row — one token each.

An example

Each player has 2 tokens. White blunders the queen, and Black takes it. White gives a token and takes the move back: the queen is back, White to move. Now White has 1 token and Black has 3 — Black has more room for the next mistake. Every blunder you fix is paid for with your opponent’s right to fix one of theirs.

Checkmate and stalemate

If you are checkmated or stalemated while you still hold a token, the game does not end at once. You decide: take the move back — the token goes to your opponent and you look for another move — or accept the result: checkmate is a loss, stalemate a draw. Your clock runs while you decide; if it runs out, the result on the board stands. Without tokens, checkmate and stalemate end the game as usual.

What stays the same

Everything else follows the Chess960 rules: castling, en passant, promotion, a draw by agreement, resignation, repetition, the 75-move rule, insufficient material, losing on time. You cannot take a move back on your opponent’s turn or before you have made a move yourself.

Why tokens change hands

An ordinary take-back on request breaks a game: whoever asks more often wins. In Undo Chess, fixing a mistake costs a token, and that token strengthens your opponent. So spending one is a chess decision too: fix the blunder now, or save the token for the endgame, where mistakes cost more.

For a beginner and a stronger friend, it lets a game be played out instead of lost to a single blunder. For equal opponents, it adds one more thing to calculate.

Where to play

In a game with a friend via a link — on this website and in the Android app. Create an invite, choose how many tokens each player gets and send the link.

Rated games and arenas follow the standard Chess960 rules, without tokens.

Play Undo Chess with a friend

Questions