Crazyhouse is a chess variant in which captured enemy pieces can be reintroduced, or dropped, into the game as one's own. It was derived as a two-player, single-board variant of bughouse chess.
Its drop rule is reminiscent of shogi [1] [ better source needed ] and the games are often compared, though there is no known evidence suggesting that shogi provided direct inspiration for the gameplay of bughouse or crazyhouse.
Though the four-player "bughouse" chess became prominent in western chess circles in the 1960s, the crazyhouse variant did not rise to prominence until the era of 1990s online chess servers, though it may be traced back further to the "Mad Mate" variant made in 1972 by Alex Randolph, a Bohemian-American game designer who moved to Japan and became an amateur dan-level Shogi player. [2]
The rules of chess apply except for the addition of drops, as explained below.
Unlike in shogi, dropping a pawn on a file containing another pawn of the same color and dropping a pawn to deliver checkmate are both permissible. [4] [ better source needed ]
Crazyhouse's notation system is an extension of the standard algebraic notation. A drop is notated like a standard move, except an at sign is placed immediately before the destination square. For example, N@d5 means "knight is dropped on d5." [3] [ better source needed ]
There is no standard FEN specification for Crazyhouse. Lichess uses an extended version of FEN, adding a 9th rank as a reserve. Here is an example of Lichess's FEN implementation: [5]
r2qk3/pp2bqR1/2p5/8/3Pn3/3BPpB1/PPPp1PPP/RK1R4/PNNNbpp b - - 89 45
In XBoard/Winboard's notation system, the reserve is given in square brackets following the board position:
r2qk3/pp2bqR1/2p5/8/3Pn3/3BPpB1/PPPp1PPP/RK1R4[PNNNbpp] b - - 89 45
In Chess.com's notation system, the reserve is located after the full-move number.
To keep track of which pieces are promoted, Lichess and XBoard/Winboard use "~" after the letter designation. Chess.com uses the coordinates of the pieces. [6] [ failed verification ]
r2q1r1k/2p1ppb1/p2p2pp/3P1p2/B6B/2N2NPp/1PP2P1K/3Q3q w - - 0 26 NNBRpr h1
GM Larry Kaufman wrote: "[Crazyhouse] is rather fun and interesting, but the games tend to be short, and it is almost certain that White has a forced win, although it would probably be too difficult to prove this and certainly too difficult to memorize all the possible variations." [7]
Algebraic notation is the standard method for recording and describing the moves in a game of chess. It is based on a system of coordinates to uniquely identify each square on the board. It is now almost universally used by books, magazines, newspapers and software, and is the only form of notation recognized by FIDE, the international chess governing body.
Bughouse chess is a popular chess variant played on two chessboards by four players in teams of two. Normal chess rules apply, except that captured pieces on one board are passed on to the teammate on the other board, who then has the option of putting these pieces on their board.
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The Universal Chess Interface (UCI) is an open communication protocol that enables chess engines to communicate with user interfaces.
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Chu shogi is a strategy board game native to Japan. It is similar to modern shogi in its rules and gameplay. Its name means "mid-sized shogi", from a time when there were three sizes of shogi variants that were regularly being played. Chu shogi seems to have been developed in the early 14th century as a derivative of dai shogi. There are earlier references, but it is not clear that they refer to the game as we now know it.
Yari shogi is a modern variant of shogi ; however, it is not Japanese. It was invented in 1981 by Christian Freeling of the Netherlands. This game accentuates shogi’s intrinsically forward range of direction by giving most of the pieces the ability to move any number of free squares orthogonally forward like a shogi lance. The opposite is true of promoted pieces which can move backward with the same power.
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Dai shogi or Kamakura dai shogi (鎌倉大将棋) is a board game native to Japan. It derived from Heian era shogi, and is similar to standard shogi in its rules and game play. Dai shogi is only one of several large board shogi variants. Its name means large shogi, from a time when there were three sizes of shogi games. Early versions of dai shogi can be traced back to the Kamakura period, from about AD 1230. It was the historical basis for the later, much more popular variant chu shogi, which shrinks the board and removes the weakest pieces.
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Shogi notation is the set of various abbreviatory notational systems used to describe the piece movements of a shogi game record or the positions of pieces on a shogi board.