This is a simplified version of chess, played on a 6×6 (rather than 8×8) board without bishops. Pawns can move only one space forward, and there is consequently no en passant capture. In this modified version, castling is allowed, along with pawn promotion to a previously lost piece. There is no automation in this Demonstration. Players must make moves manually, by dragging a piece. Captured pieces must be dragged to the gray sideline. Just as in a noncomputerized board game, players are responsible for making only legal moves and declaring "king in check", "checkmate", or "stalemate" when appropriate. Two players can use separate computers connected on a Wi-Fi network.
During 1956, I was a summer student at Los Alamos National Laboratory. This was the home of the MANIAC I, back then one of the most powerful computers in the world. Its main function was to perform intricate calculations of thermonuclear processes. Some of the resident computer scientists became interested in programming computers to play chess. Since even the MANIAC lacked the computational power to play a full orthodox game, some simplified variations were considered. This was when I invented the 6×6 version of chess described in this Demonstration. After I left my summer job, a chess-playing program for MANIAC I was written by Stanislaw Ulam and colleagues. The program was successively improved for several years thereafter.
Los Alamos scientists Paul Stern (left) and Nick Metropolis playing chess using the MANIAC computer.