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  (Tandem Chess)

Bughouse (or siamese chess) is a "wild" variant of chess played between two player teams on two separate boards. The special feature of the game is that pieces you capture are transferred to your partner, who is playing with the opposite color pieces from yourself. He may "drop" such a piece on an empty square as a subsequent move in his game.


First, use the "partner" command to select a partner. Next, find an opponent team. You may use the Team channel for this purpose (channel 25), and the command "who B" lists players who are members of a current bughouse team.

Then, one of your team challenges his desired opponent on the other team to a "wild bughouse" match. (A useful alias for this is "alias bug match  @   2 12 bughouse" where "bug user_name" is all you would need to type in order to match user_name to a bughouse game.)

When the match is accepted and all four players are present, then two games are initiated simultaneously: one between the challenger and the challengee with the desired colors, and one between the other partners, with colors opposite from their partners. The same time control applies to both boards, though "moretime" can be used independently on each board. Each player is notified of the game number of their partner's game, so he may observe it as well as playing in his own game.

To help you form bughouse partnerships and bughouse matches, two channels have been established: channels 24 and 25. Channel 24 is for matches and channel 25 is for partnerships.


As you play, you will be periodically notified when your partner passes you captured pieces. You will be told the piece that was passed, and the set of pieces that you are currently holding. You are also notified when your opponent's holdings change. Both player's holdings are displayed whenever your board position is refreshed.

A new move notation is needed to drop one of your held pieces onto the board. The notation for making a drop is "P@fr", where P is a piece you are holding [PNBRQ] and "fr" is the empty destination square.

You may talk to your partner. It is recommended to set up convenient aliases for common messages, such as "I need a knight!!", "Don't give him a bishop!", and "Are you out of your mind?!". The "ptell" command is used for this purpose; only your partner will hear it.

The match is finished when one player is checkmated, resigns, or is flagged. At that point the wild ratings of all match players are adjusted, whether or not the team result was because of their game. A draw request should be made and accepted at both boards before the match is ended as a draw (a near impossibility).

Note that checkmate is defined differently: there must be no possibility of avoiding checkmate by a drop interposition. Even if your opponent is holding no pieces that he can drop, he may later get a piece to interpose from his partner. Thus, only contact and knight checks can give a "decisive" checkmate.


Pawns cannot be dropped onto your first or eighth rank, although they may be dropped onto the seventh rank and promoted on the next move.

Pieces that had been promoted revert to pawns when captured and passed to your partner.

Your partner variable is not saved between logins. You should set it prior to starting your first bughouse match in a server session and when you want to change partners.

Observers should observe both games to see the full match. Kibitzes and whispers, however, go to observers (and players) of both games. Observers will also be notified of pieces transferred to each player's reserves. (Note that kibitz can be used as a shortcut to tell your partner something if you don't mind your opponents hearing it. It also makes the game more exciting for the observers.)

Strength assessment takes held pieces into account.

This mode of play may break client interfaces. Contact the author of your client to determine if you can play bughouse with it. If a client relies on the board position rather than moves, things should work OK. No new styles have been added to support bughouse.

Because this is such a nonstandard type of play, there are a number of commands that are not applicable to a bughouse game:

  1. The move record is not saved. Adjournments and disconnections end both games and the match cannot be resumed. (This leaves a lot of room for abuse, but hey, bughouse is just for fun, guys!) Disabled commands are: adjourn, sposition, mailstored, examine, mexamine, unexamine, backward, forward, revert.
  2. Simul commands cannot be used for bughouse games. [FDA regulation to avoid frying the brains of the participants. :) ]
  3. Takeback is disabled (for now). At best, takeback would work only on noncapture moves (including drops) to avoid having to take held pieces away from the other game.
  4. Switch is disabled (for now).
  5. Moves, oldmoves, mailmoves and mailoldmoves do work during a game, but they now break the PGN format, which doesn't allow drops. Moves are shown as "P/@@-fr" and "P@fr" in the old and PGN formats. Only moves and drops are recorded, not changes to a player's holdings. Theoretically, knowing the duration of each move in both games allows you to reconstruct the holdings as well. (But who'd want to analyze or store a bughouse game??)
  6. Except for commands which terminate a game, commands affect only one of the two games in a bughouse match.

For notes on strategy in bughouse chess, see the "bughouse_strategy" help file.

See also: bughouse strategy, match, partner, ptell, set, variables, wild

next up previous contents
Next: bughouse strategy Up: Informational Files Previous: blitz

Klaus Knopper <>