Full Rules

Setup

• Two boards, four players, two teams. Board A and Board B are played at the same time. Each team has two players, one on each board.
• Teammates play opposite colors on opposite boards. The pairings are fixed: White on Board A partners Black on Board B, and Black on Board A partners White on Board B.
• Both boards start from the standard chess starting position, and each board runs on its own pair of clocks.

Standard chess on each board

On your turn you make either a normal chess move or a drop (see below). All the usual chess rules apply on each board:

• Castling — the king and rook must not have moved, no pieces between them, and the king may not castle out of, through, or into check.
• En passant — a pawn that just advanced two squares from its starting rank can be captured by an adjacent enemy pawn, on the very next move only.
• Promotion — a pawn reaching the last rank promotes to a queen, rook, bishop, or knight. (The play page currently auto-promotes to a queen.)
• Check, checkmate, and stalemate are detected as in standard chess.

Three-fold repetition and the 50-move rule are not enforced in Bughouse. The constant flow of pieces makes repeated positions rare, and the clocks settle games that drag.

Piece passing and pockets

This is the defining rule of Bughouse. When you capture a piece on your board, it goes to your teammate's pocket on the other board — not your own. Your teammate can later drop it as one of their pieces.

• Captures by White on Board A arm Black's pocket on Board B (White-A and Black-B are partners), and symmetrically for every other seat.
• The piece takes your teammate's color in their pocket; its type is whatever was captured — with one important exception below.

Promoted pieces revert to pawns

A pawn that has promoted is still "really" a pawn. If a promoted piece is captured, a pawn is delivered to the capturer's partner — not the promoted piece type. Example: a white pawn promotes to a queen on a8; Black later captures that queen; Black's partner receives a pawn in their pocket, not a queen.

Drops

Instead of moving a piece, you may drop a piece from your pocket onto the board. A dropped piece is your color and is subject to these restrictions:

• Drops land on empty squares only. You cannot capture by dropping.
• Pawns may not be dropped on the 1st or 8th rank — no instant promotion via drop.
• A dropped piece can give check, including a discovered check.
• A dropped rook cannot be castled with. It counts as having moved, even though it arrived from the pocket.
• A dropped pawn cannot be captured en passant. En passant requires the pawn to have just moved two squares from its starting rank, and a drop does not qualify.
• Drop-mate is a per-match variant rule. By default, delivering checkmate with a drop is legal. A match can be configured to forbid it, in which case a drop that would give immediate checkmate is rejected — other checks by drop remain fine.

Clocks

• Each board has its own pair of clocks; your clock runs only while it is your move on your board.
• Time controls — initial time, and any increment or delay — are configured per match and apply to both boards.
• Running out of time ("flagging") on either board ends the whole match — the team whose player flagged loses.

Winning the match

Bughouse is won by the team, and either board can end the match:

• Checkmate on either board ends the match — the team whose player was mated loses.
• Flag-fall on either board ends the match — the team whose player ran out of time loses.
• Resignation ends the match in the other team's favor.
• A mutual abort, agreed by both players, ends the match without a winner.

Communication and etiquette

Talking to your teammate is part of the game — coordinating trades, asking for pieces, and warning about threats is expected, not cheating.

• Use the in-game signals bar to coordinate: sit (wait, don't move), go (play on), hold a piece, ask for the piece you need, plus quick courtesies like OK, sorry, and thanks.
• You may tell your partner what to capture or when to stall, but only your teammate — coordinating with the opposing team's players is not part of the game.
• Be a good sport: win with grace, lose with a "good game", and keep the trash talk friendly.

Keep learning

Head back to Learning for more guides, or jump into a game from the Play page.