An Antichess board with standard location notations
Antichess is a variant of chess in which the goal is to either lose all of your pieces (except your king) or checkmate your opponent. A related variant of Antichess, referred to here as Anti-King Antichess, consists of Antichess with the addition of an anti-king playing piece for each player which functions as a king but is considered to be in check whenever it is not under attack by an opponent piece. The purpose of this program is to play either Anti-King Antichess or standard Antichess between two players, either of which may be human- or computer-controlled. Direct gameplay may occur via graphical and textual interfaces; a third mode of use allows for Internet-based play.
Antichess is played between two opponents by moving pieces on a square board. The board is composed of 64 equal squares. The eight vertical lines of squares are called columns. The eight horizontal lines of squares are called rows. The squares are colored black and white alternately. The lines of squares of the same color, touching corner to corner, are called diagonals. The chessboard is placed between the players in such a way that the near corner to the right of each player is white. The columns are labeled a to h from left to right. The rows are numbered 1 to 8 from bottom to top.
At the beginning of the game, one player ("white") has 16 white pieces, and the other ("black") has 16 black pieces. The white player pieces are: one King (e1), one Queen (d1), two bishops (c1 and f1), two knights (b1 and g1), two rooks (a1 and h1), and eight pawns (row 2). The black player pieces are: one King (e8), one Queen (d8), two bishops (c8 and f8), two knights (b8 and g8), two rooks (a8 and h8), and eight pawns (row 7). The initial position of the pieces on the chessboard is shown to the right.
Two additional pieces are added to the starting board in Anti-King Antichess: one anti-king for white (d6) and one anti-king for black (d3).
A move is defined by the following rules:
A player's moves are limited by the following fact: A player is forced to capture an opponent's piece whenever possible. If a player can take several of the opponent's pieces, he/she is free to choose which piece to take. This limitation does not exists in regular chess. See the exceptions to this rule.
An anti-king may move to any of the eight squares immediately surrounding it so long as making the move does not place it in anti-check. Anti-kings do not attack opposing pieces; rather, they attack the player's own pieces (i.e., the black anti-king attacks black pieces and the white anti-king attacks white pieces). If an anti-king can attack and capture a piece of its own color, it must do so unless doing so results in check or anti-check. Anti-check occurs when an anti-king is no longer directly attackable by any pieces controlled by its opponent. If an anti-king comes into anti-check, it is the controlling player's responsibility to ensure that his move removes the anti-king from anti-check. If he cannot do so, then an anticheckmate has occurred, and the player controlling the anti-king loses the game. See also Handling Check and Anti-Check Situations.
All the other pieces move exactly as they do in standard chess, including special moves such as en passant and castling. Additionally, the king is placed in check in exactly the same way as in standard chess. There is only one variation in Antichess:
In short, each move of player A must observe the following:
The following additional restrictions apply when Anti-King Antichess is being played:
The king is in check when the square it occupies is attackable by one or more of the opponent's pieces; in this case, the latter is/are said to be checking the king. A player may not make a move which leaves his king on a square attackable by any of his opponent's pieces; e.g., the player cannot move the king into check. Check must be resolved by the move immediately following. If any check cannot be parried, the king is said to be checkmated or mated.
It is the foremost obligation of each player to move the king out of a check (and, in Anti-King Antichess, to move the anti-king out of anti-check). This overrides the rule that you must take an opponent's piece. For example, in the figure below to the left , it is black's turn and black must move its king out of check even though it can take white's bishop on c6 with its rook.
If it is possible for a player to remove the king from check (or the anti-king from anti-check) as well take a piece of the opponent, then the player must do so. For example, suppose the black player's king is under check from white's rook. Further, suppose black has two choices to move away from check — remove the check with or without taking a white piece. In that case, black must take white's piece and remove the check.
Antichess is played with time restrictions as typically occurs in chess games. Each player is allocated a fixed amount of time T to make all the moves, e.g., 5 minutes. There is a clock for each player that is set to T minutes at the start of the game. If it is player A's turn to move, A's clock counts down until the move is made. While it is B's turn to move, A's clock is suspended, and B's clock runs down. If a player's clock runs down to zero while the game is in progress, the player loses. This ensures that the game is over in less than 2*T minutes, because by then at least one of the clocks has run down to zero.
In standard Antichess, player A wins the game against player B if:
If player A checkmates player B and on the same turn takes the last of player B's non-king pieces, player A wins (i.e., the checkmate prevails).
In Anti-King Antichess, player A wins the game against player B if:
If player A checkmates player B and on the same turn takes a piece leaving B with just 3, player B wins (ie, the loss of pieces prevails). Note that this is different from standard antichess, where the checkmate would prevail.
The game is stalemated if the king of the player who has the move is not in check, and this player cannot make any legal move. In the example on the right, black is stalemated on their turn, since neither their pawns nor king can move. In antichess, the stalemated player loses his turn, and the opposing player may continue to take turns until the stalemate is broken or the game is won. The result of a game where both players are stalemated is undefined.
Antichess requires that Java Web Start (JAWS) is properly installed on the user's machine. Users may download the application from our web site. Note that in order to save or load games, the "Always trust content from this source" box should be checked.
The general layout of Antichess includes a board, timers, and a move history table. The board displays the current pieces still in play. The board is in standard layout with White towards the bottom, and Black (pieces in red) at the top. On a human move, legal pieces will have their squares highlighted in yellow. Above and below the board are the timers for Black and White, respectively. If no timers are set for a particular color, the word "Untimed" will appear in place of the remaining time. Time is given in mm:ss format. To the right of the board is the move history table, listing the moves made by White and Black. Moves are written in a simplified chess format.
To start a new game, select File > New Game from the menu bar or press F2. A New Game dialog will appear. Select the desired game settings. Either humans or computers can play as white or black. Timing may be enabled for both, one, or no players. To set one of the players as a computer player, select the desired level from the dropdown box. An additional "Play with anti-kings" checkbox at the lower left of the dialog allows the user to specify the Anti-King version of Antichess for the current game.
When you have made your selections, click "OK" to start the game. A new board will appear on the screen, with timers if appropriate or "Untimed" if no time limit is set. A blank move history table will also appear to the right of the board.
In order to save the current game, select File > Save Game from the menu bar or press Ctrl+s. The Save Antichess Game dialog will appear. Enter a filename for the game and click "Save" to save the game. Note that this operation may fail if the application is not given security privileges. Player settings are not saved. The game file will not contain information about whether players are human or computer.
To load a game, select File > Load Game from the menu bar or press Ctrl+o. The Load Antichess Game dialog will appear. Select the desired game and click "Open" to load the game file. An error message will appear if the file is not a valid xml Antichess game.
Games may be saved or loaded at any point, even if they have already terminated.
The user may make a move only when it is a human turn. To make a move, drag and drop a highlighted piece to its new position. When a piece is clicked, the legal moves are highlighted in yellow. Note that if no legal move is available, the player loses his turn.
New moves will appear in the move history list. If the current move ends the game, a dialog will appear informing the user of the winner.
To pause the game, click "Pause" at the bottom of the screen. The word "Paused" will appear, hiding the board. To return to your game, click "Unpause" at the bottom of the screen. Play will then resume.
To close Antichess, select File > Exit from the menu bar, or click the red "X" at the upper right corner of the application. You may close the application at any time, except from a dialog screen. You must close all dialogs before exiting Antichess.
All moves used in the Antichess application follow this standard format:
<move-desc> ::= <position>-<position> <position> ::= <col><row> <col> ::= a | b | c | d | e | f | g | h <row> ::= 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8
As an example, the opening move a7-a6 represents the pawn move from square a7 to the square above it, a6. Please refer to the board diagram for further clarification of square labelling.
Last Modified: Sunday, May 14, 2006 by lye