Crazyhouse

Crazyhouse is a variant of chess similar to bughouse, except that it is played between only two players, on one board. The special feature of the game is that when you capture a piece, you receive a piece of the same kind, but of your color. Rules for piece 'drops' are the same as in bughouse, i.e. any piece may be dropped on any open square with the exception that pawns may not be dropped on the 1st or 8th rank.

Starting a Crazyhouse game:

Starting a crazyhouse game is just like starting any other game, except that you must specify the type as crazyhouse rather than the default. To begin, either...

Challenge someone directly and specify crazyhouse in the type field
Advertise your interest with a seek ad with crazyhouse specified in the type field

Playing Crazyhouse

Once the game has started, your board will appear with the captured pieces display, regardless of the option of the settings dialog, because captured pieces are a necessary part of the game. After moving normally at first, when you take a piece, you will have a board window that looks something like:

White has taken a Queen and a pawn. These pieces may now be dragged from the captured pieces display onto the board as a move, provided it is not a pawn on the first or 8th ranks and that the resulting position is legal.

For checkmate to occur, there must be no possibility of avoiding checkmate by a drop interposition. This means either the opponent is not holding any pieces, or in the case of check along the 1st or 8th rank by a queen or rook, he holds no pieces other than pawns. It is also possible to checkmate by contact checks, knight checks, and double checks.

To claim a draw by repetition, the same board position must be reached 3 times with the same player to move. The count restarts whenever a pawn is moved, a capture is made, or a piece is dropped. Note that this may be inadequate for some situations where each player drops a particular piece, which is immediately exchanged, then dropped again etc.

Special Notes:

Unlike bughouse, takebacks are allowed.
Pieces that had been promoted revert to pawns when captured.
If you do not want to play crazyhouse games, you can set up a formula to automatically decline match requests for Crazyhouse.
Crazyhouse games are denoted in 'games' and 'history' listings by "23r" (or 23u)
The Tomato bots occasionally run Crazyhouse tourneys.