Bughouse chess  Bughouse chess (also known as exchange chess, Siamese chess (not to be confused with makruk), tandem chess, transfer chess, double bughouse, cross chess, swap chess or simply bughouse or bug) is a popular chess variant played on two chessboards by four players in teams of two. Normal chess rules apply, except that captured pieces on one board are passed on to the teammate on the other board, who then has the option of putting these pieces on their board. The game is usually played at a fast time control; this, together with the passing and dropping of pieces, can make the game look chaotic 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 organized 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, with the exception of the rules specified below. A player capturing a piece immediately passes that piece to the capturing player's partner. The partner keeps these pieces in reserve and may, instead of playing a regular move, place one of these pieces on the board (as in shogi and crazyhouse), called "dropping" the piece. Pieces in reserve or on deck may be dropped on any vacant square, including squares where the piece delivers check or checkmate; however, pawns may not be dropped on the first or last . Dropped pawns may promote, but all promoted pawns convert back to pawns when captured. In play over the board, a promoted pawn can be put on its side to indicate promotion. A pawn placed on the second rank may move two squares on its first move. Each player must keep the reserve or stock pieces on the table in front of the board, always visible to all players of the game. Bughouse chess is usually played with chess clocks to prevent players from waiting indefinitely for a piece. Clocks are placed on the outside so that each player can see both clocks. At the start of the game, the players with the black pieces start the clocks simultaneously. Bughouse is usually played using , which allows touching of pieces.