Los Alamos chess

How Los Alamos chess is played

Los Alamos chess is chess on a 6 × 6 board without bishops, written in 1956 for the MANIAC I computer.

The board and the start

Six files, a to f, and six ranks. On the first rank from a1: rook, knight, queen, king, knight, rook; the pawns on the second; Black the same on the far side.

Pawns

A pawn moves one square forward and captures one square diagonally forward; there is no double step and no en passant. On the last rank it becomes a queen, a rook or a knight.

Winning and draws

Checkmate wins. Stalemate, the same position three times, fifty moves each without a capture or a pawn move, and too little material to mate are draws. There is no castling.

The story

Los Alamos · the MANIAC I’s game of 1956

When and where

Los Alamos chess was written in 1956 by Paul Stein and Mark Wells for the MANIAC I computer at the Los Alamos Scientific Laboratory. The board was cut down to six by six squares and the bishops left out because the computer had so little capacity.

How it changed

The program was about 600 instructions long. It looked four plies ahead, weighing material and mobility, and took about 20 minutes a move.

Today

It is remembered as the first chess-like game played by a computer program, and engines such as Fairy-Stockfish still play it.

Did you know?

The computer played three recorded games: against itself; against Martin Kruskal, a strong player who gave it queen odds and won; and against a laboratory assistant who had learnt the rules a week before. The computer won that one, the first time a computer beat a human at a chess-like game.

Sources: Wikipedia

More games

Chess and variants

• Chess · Classic chess, Chess960, or Los Alamos chess on 6 × 6 (1956).
• Chess960 · Fischer random chess: the back rank starts in one of 960 setups.
• Antichess · Losing chess: give away all your pieces, captures are compulsory.
• Atomic chess · Every capture is an explosion that clears the pieces around it.
• Crazyhouse · Captured pieces change sides and can be dropped back onto the board.
• Three-check · Chess where the third check wins, so every check counts.
• King of the Hill · Chess where a king that reaches the centre wins at once.
• Racing Kings · No pawns, no checks: the first king on the far rank wins.
• Horde · 36 white pawns storm a full black army.
• Dunsany’s chess · Lord Dunsany’s game of 1942: 32 pawns against a full army.
• Duck chess · After every move you move the duck, which blocks everyone. No check.
• Fog of War · You only see where your pieces can move. Capture the king to win.
• Kriegspiel · Only your own pieces in sight; an umpire judges every move.
• Friendly Chess · Nothing is captured: pieces unite and set off chain reactions.

The chess family

• Chaturanga · India’s ancient chess, the root of the family: take the king to win.
• Shatranj · The medieval ancestor of chess, with a weak ferz and a jumping alfil.
• Medieval chess · Europe’s chess before 1475: the ferz and the king may leap on their first move.
• Courier chess · Medieval Germany’s chess on a 12 × 8 board, with the courier, the man and the schleich.
• Tamerlane chess · Timur’s great chess on an 11 × 10 board, with giraffes, camels and citadels.
• Makruk · Thai chess: a slow, strategic game with a counting rule.
• Ouk Chatrang · Cambodian chess: Makruk with a leap for the king and the met.
• Sittuyin · Burmese chess: set up your pieces, then promote on the diagonals.
• Kar Ouk · Ouk Chatrang where the first check wins: guard your king.
• Xiangqi · Chinese chess: a river, palaces and a cannon that jumps to capture.
• Janggi · Korean chess: no river, palace diagonals and a cannon that always jumps.
• Shogi · Japanese chess: captured pieces return to the board on your side.
• Minishogi · Shogi on a 5 × 5 board: six pieces a side, short and sharp games.

More players

• Chaturaji · India’s four-handed chess: kings can be captured, captures score.
• Four Seasons Chess · Alfonso X’s chess for four from 1283: four seasons, the last king wins.
• Three-player chess · Three armies on a hexagonal board: you against two bots.
• Four-player chess · Four armies on a cross-shaped board: in teams or all against all.
• Verney’s four-handed chess · Verney’s game of 1881: two against two, mate both enemy kings.
• Bughouse · Two boards, two teams: what you capture goes to your partner's hand.
• Eight-player chess · Eight armies on a board of 516 squares: all against all, in pairs or four against four.