Bughouse chess and random to the casual onlooker; hence the name bughouse, which is slang for mental hospital. The game is traditionally played as a diversion from regular chess both over the board and online. Yearly, several dedicated bughouse tournaments are organised on a national and an international level. Bughouse is a chess variant played on two chessboards by four players in teams of two. Each team member faces one opponent of the other team. Partners sit next to each other and one player has black, while the other has white. Each player plays the opponent as in a standard chess game,
Kriegspiel (chess) follows. The game is played with three boards, one for each player; the third is for the umpire (and spectators). Each opponent knows the exact position of just their pieces, and does not know where the opponent's pieces are (but can keep track of how many there are). Only the umpire knows the position of the game. The game proceeds in the following way: The umpire announces: Pawn promotions are not announced. Kriegspiel is sometimes used in chess problems. In these, usual variations introduced by different black moves are replaced by variations introduced by different announcements. An example of a