Marseillais chess Marseillais chess Marseillais chess (also called Double-Move chess) is a chess variant in which each player moves twice per turn. The rules of the game were first published in Marseillais local newspaper "Le Soleil" in 1925. The variant became quite popular in the late 1930s with such chess grandmasters as Alexander Alekhine, Richard Réti, Eugene Znosko-Borovsky, and André Chéron playing it. A player can either move one piece twice or move two different pieces on his turn. Castling is considered a single move. When a player gives check on the first move, he loses the second move of his turn.
Null-move heuristic of chess positions where employing the null-move heuristic can result in severe tactical blunders. In these "zugzwang" (German for "forced to move") positions, the player whose turn it is to move has only bad moves as their legal choices, and so would actually be better off if allowed to forfeit the right to move. In these positions, the null-move heuristic may produce a cutoff where a full search would not have found one, causing the program to assume the position is very good for a side when it may in fact be very bad for them. To avoid using the