This game, created by Fabrice Liardet, is an original chess variant with simple rules but a deep strategy. The basic rules are identical with the classic chess, but there are several significant exceptions.
Short version: One selects the destination square, but the opponent selects which piece moves there.
- Instead of clicking on piece to move and then on a destination square, a player marks a destination square and submits this unfinished move.
- Then it is up to the opponent to choose which player’s piece will actually move to the marked square (of course, only the pieces which really can make a move to the destination square can be selected). When it is done and the move is completed, the opponent marks a square to move their own piece to, etc.
- If only one piece can move to the marked square, the full move is performed immediately without waiting for the opponent’s choice (because there is only one possibility).
- If a pawn reaches the last row, it is the opponent who chooses which piece the pawn will be promoted to.
- Castling is not possible.
- There is no check or checkmate. The goal is to capture the opponent’s king.
I have a special relationship with this chess variant, maybe because I got the opportunity to participate in its popularization. I remember Fabrice contacting me sometime in 2006 asking if I would be willing to implement Ambiguous Chess on my game server BrainKing.com. It’s always gratifying when the author of something interesting addresses you directly, but in this case, it was also an interesting challenge from a programming point of view. So far, I’ve only programmed games with clear moves – White moves and gives full control to Black, then Black moves and gives the initiative back to White, etc. It was definitely not easy to hack the engine to support “half” shared moves. But I succeeded and even today, after almost seventeen years, I do not regret my decision.
Okay, enough nostalgia and history lessons, let’s see some games! I would start with a trap that can be very effective against novice players who still struggle with the basic principles of the Ambiguous Chess.
1. e4 e5 (White pointed to the square e4 and since there is only one piece to make a valid move there, Black completed the move with the pawn. Similarly, Black played the unambiguous first move with their own e-pawn.)
2. ?c4 (And the ambiguous element is already taking its place. White marked the field c4, which allows making two different moves: 2. c4 – pawn, or 2. ♗c4 – bishop. Black selected the bishop.)
2. (♗c4) ?d6 (It wasn’t the best idea to let White develop the bishop, but Black’s second half-move is already a blunder. Regardless of the black piece selected by White, the fate is already determined.)
2. … (d6) 3. ♗xf7! (Again, the only move to the target square f7, so Black must choose the white bishop.)
3. … ♚xf7 (The king must capture the bishop. Any other half-move would end with capturing the king.)
- 3. … ?d7 (blue marker): 3. … ♛d7 (White selected the queen) 4. ♗xe8
- 3. … ?e7 (yellow marker): 3. … ♝e7 (White selected the bishop) 4. ♗xe8
4. ♕h5 (Only the queen can reach the target square h5. The game is over, as the black king is unable to retreat, and will be captured in the next move. See the diagram.)
The only three options to get the king outside the deadly diagonal h5-e8 are reachable by other pieces as well:
- Blue: Queen, bishop, knight.
- Yellow: Bishop.
- Red: Queen, knight.
Back in 2006, I challenged the author himself. My total defeat wasn’t a big surprise, but at least I learned something about the strategy.
If you would like to learn more about this fascinating variant, I recommend visiting the author’s site, where you can find a huge amount of information, tips, openings, sample games, and a lot more.