Chess rules =========== /cs implements standard chess rules - including castling, en-passant, under-promotion, and stalemate - which you can find elsewhere. On /cs a game ends in a draw - if none of the last 50 half-moves have been irreversible (i.e. no captures and no pawn moves), regardless of the board size or endgame type. - if a position is repeated three times. Positions are considered equal if all squares contain the same piece type(!) and the castling status, the en-passant status, and the color to move is equal. In order to support komi and synchro modes /cs introduces a novel scoring system which allows a fine grained score similar to board games like Go or Othello and encourages players to play efficiently. From the winner's perspective the score of a game is (1000-#moves played by the winner). Draws are scored as 0. E.g. suppose WHITE won a game that lasted 41 half-moves. Then WHITE played 21 moves and the score for WHITE is 1000-21= 979. BLACK'S score then is -979. (N.B.: This scheme assumes that no more than 999 moves are played in a chess game on /cs, which sounds reasonable. Graphical GGS user interfaces can help with the arithmetic by converting intuitive komi inputs into the format /cs requires (e.g. 21 -> 979) before sending it to GGS) Please refer to "random" to see how /cs generates random starting positions.