Crazyhouse

What this variant is

Crazyhouse is standard chess with one addition taken from shogi: pieces you capture are not removed from the game. They change colour, go into your hand, and can be returned to the board later. The starting array, the piece moves, castling, capture in passing and promotion are all otherwise unchanged.

Your hand is public. Both players can see what each other is holding, so a hidden reserve is never part of the game.

Drops

On your turn you may either move a man on the board, as usual, or drop one piece from your hand. You may not do both, and a drop uses your whole turn.

• A dropped piece may go on any empty square, with one exception below. It does not have to be near anything and it does not have to be defended.
• A pawn may never be dropped on the first or the last rank. That is the only square restriction in the game.
• A drop may give check, and a drop may be checkmate. A knight dropped beside a castled king is the commonest finish in the whole variant.
• You may not drop a piece to escape check by placing it on the king’s own square, for the obvious reason, but you may drop a piece to block a check along a line.
• Kings are never captured and so never enter anyone’s hand.

Promotion works normally: a pawn reaching the far rank becomes a queen, rook, bishop or knight. But the board remembers what it really is. When a promoted piece is captured, it goes into the capturer’s hand as a pawn, not as the piece it had become. Capturing a promoted queen therefore gains you a queen’s worth of material and a pawn in hand.

Capture in passing still works, and the pawn taken that way goes to your hand like any other capture.

Winning

• Checkmate, including checkmate delivered by a drop. The defender must be able to answer the check with a legal move, and a drop of their own counts as one.
• Resignation, or the opponent running out of time.

Drawing

Stalemate is a draw, as are agreement, threefold repetition and the fifty-move rule, which are applied automatically for both sides. Note that a position repeats only if both hands are also the same, so repetition is much rarer here than in standard chess.

Draws for a dead position are effectively impossible: with pieces flowing back onto the board, almost any material can produce a mate.

How it changes your play

• Material counts for far less than usual. Giving up a piece to open a line at the king is often winning, even though the opponent now holds that piece.
• Never leave a weak square near your king undefended. In standard chess an attacker has to walk a piece there. Here they just put one there.
• Think before you capture. Every capture arms your opponent as well as you, and sometimes the right move is to leave a piece standing.
• Pawns in hand are undervalued by beginners. A pawn dropped on the sixth or seventh rank is a promotion threat that costs one move to create.