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1.N@e7+ Kh8 2.Bxg7# (@ notation)

Crazyhouse (also known as drop chess, mad chess, reinforcement chess, turnabout chess and schizo-chess) is a chess variant similar to bughouse chess, but with only two players. It effectively incorporates a rule from the game shogi, in which a player can introduce a captured piece back to the chessboard as their own.


All the rules and conventions of standard chess apply, with the addition of drops, as explained below.

  • A captured piece reverses color and goes to the capturing player's reserve, pocket or bank. At any time, instead of making a move with a piece on the board, a player can drop a piece from their reserve (a piece in there is considered “held” or “in hand”) onto an empty square on the board. For example, a check that would result in checkmate in standard chess can be answered in Crazyhouse, if the defender can play a legal drop that blocks the check.[1]
  • Drops resulting in immediate checkmate are permitted. Unlike in shogi, this includes pawn drops.[2]
  • Pawns may not be dropped on the 1st or 8th ranks.[2]
  • Pawns that have been promoted and later captured are dropped as pawns.[2] (As in shogi.)

Unlike in shogi, having two or more pawns on a file, as well as checkmating with a dropped pawn, are both permissible.


An extension to the standard chess notation is used to record drops. Drops are notated by the piece type, followed by an @ symbol, then the destination square. For example, N@d5 means "knight is dropped on d5 from reserve".[1]


There is no standard FEN specification for Crazyhouse. However at Lichess an extended version of FEN is in use. Here is Lichess's FEN implemention example.[3]

r2qk3/pp2bqR1/2p5/8/3Pn3/3BPpB1/PPPp1PPP/RK1R4/PNNNbpp b - - 89 45

Lichess simply adds a 0th rank as a reserve. There are more than 8 pieces on the reserve, so the last section may have more than 8 characters.

A different notation is used by Xboard/Winboard. The reserve is given in square brackets following the board position.

r2qk3/pp2bqR1/2p5/8/3Pn3/3BPpB1/PPPp1PPP/RK1R4[PNNNbpp] b - - 89 45 uses another notation. The reserve is put after full-move number.

To keep track of which pieces currently on the board are actually promoted pawns, Lichess and Xboard/Winboard use "~" after letter designation. However, uses coordinates of promoted pawn to resolve it.[4][failed verification]

r2q1r1k/2p1ppb1/p2p2pp/3P1p2/B6B/2N2NPp/1PP2P1K/3Q3q w - - 0 26 NNBRpr h1


Minor variations of the rules have resulted in some variants.

  • Loop Chess: promoted pawns keep their rank when captured.[5]
  • Chessgi (also known as Mad Mate or Neo Chess): promoted pawns keep their rank when captured. Pawns may be dropped on the 1st rank.[6]

See also[edit]

  • Hostage Chess—a player can drop back into play their own previously captured pieces


  1. ^ a b "crazyhouse". FICS Help. Free Internet Chess Server. 2008-02-28. Archived from the original on 2014-04-16. Retrieved 2014-04-17.
  2. ^ a b c "crazyhouse". ICC Help. Internet Chess Club. Archived from the original on 2012-05-02. Retrieved 2014-04-17.
  3. ^ ""IM opperwezen vs LM JannLee in T6Q3tMva : Analysis board •"". Lichess. Archived from the original on 2018-05-26. Retrieved 2018-05-26.
  4. ^ ""Chess: liviu78ro vs JannLeeCrazyhouse - 3367504566 -"". Archived from the original on 2019-01-17. Retrieved 2019-01-17.
  5. ^ "Game rules (Loop Chess)". BrainKing. Retrieved 2014-04-17.
  6. ^ "Chessgi". 2001-03-20. Archived from the original on 2014-03-27. Retrieved 2014-04-17.

External links[edit]