Los Alamos chess

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Los Alamos chess

Los Alamos chess (or anti-clerical chess) is a chess variant played on a 6×6 board without bishops. This was the first chess-like game played by a computer program. This program was written in Los Alamos laboratory by Paul Stein and Mark Wells for the MANIAC I computer in 1956. The reduction of the board size and the number of pieces from standard chess was due to the very limited capacity of computers at the time.

The computer played three games. The first it played against itself. The second one was against a strong human player, who played without a queen. The human player won. In the third game, MANIAC I played against a novice chess player who had been taught the rules just before the game. The computer won, marking the first time that a computer had beaten a human player in a chess-like game.


The starting position is shown on the right. All rules are as in chess except:

  • There is no pawn double-move, nor is there en passant capture;
  • Pawns may not promote to bishops;
  • There is no castling.


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