Atomic chess is a chess variant. Standard rules of chess apply, but all captures result in an "explosion" through which all surrounding white and black pieces other than pawns are removed from play. Some variations additionally remove rules concerning check such that the king may be able to move into or remain in check.
Rules of atomic chess are the same as standard chess with a few important differences concerning capturing, check, and winning conditions.
When a capture is made, an explosion occurs on the destination square of the capturing piece. This explosion causes the captured piece, the capturing piece, and all adjacent non-pawn pieces to be removed from the board. Captures that result in the explosion of a player's own king are illegal; therefore, a king can never capture. [1] [2]
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Threats to the king can be direct or indirect. Putting a king in check is a direct attack and is sometimes called "atomic check". [3] An indirect threat occurs when a player threatens to explode the king by capturing an adjacent piece. In most variations of atomic chess, players must respond to being checked in a similar way they would in traditional chess—by moving the king out of check, blocking the check, or removing the checking piece—but an exception exists when the checked player can win the game by exploding the checking player's king.
As the king cannot take another piece, it is possible to move the kings next to each other without a check occurring or to escape check. This possibility is often used by a losing player to defensively position his king next to his opponent's at endgame, hoping for a draw. Depending on the board setup, this strategy is sometimes optimal and allows the draw to be forced. At other times, a player can counter by forcing a win with a position such that a piece or pawn can be exploded next to their opponent's king without blowing up their own king, or they can force the opposing king away using their king and the remaining pieces on the board, which will typically result in a loss for the retreating king.
The variant of atomic chess played at the Internet Chess Club is one that does not enforce check at all, making legal any move, even one leaving the king to be captured directly in the next move. [2] [4]
In all variations of atomic chess, a player wins by exploding the king of the opposite color without exploding their own king. This is usually done by capturing a piece on a square adjacent to the opponent's king or putting a queen next to the king which results in checkmate since a king cannot take any piece.
In variations that require a response to being checked, it is possible to checkmate an opponent to win the game, creating a situation in which a king is directly threatened and cannot make a legal move. This is sometimes called "atomic checkmate". [3] It is likewise possible for the game to end in stalemate if a king is not directly threatened and no legal moves are possible.
When typical rules of check are not enforced, victory is only attained via the explosion of the enemy king. In these variations without check, the king may be forced into check and thus capture through zugzwang.
In 1995 the German Internet Chess Server (GICS) introduced the game, based on rules one of its users collected from friends who played offline. [5] [6] It was soon after incorporated into the Middle East Wild Internet Server (MEWIS) and other smaller servers before being implemented at Chess Live and Internet Chess Club in 2000, Free Internet Chess Server in 2003 and Lichess in 2015. [7] [8] It was added to Chess.com in late 2020. In 2021, 4.9 million atomic chess games were played on Lichess. [9] Lichess also hosts 24-hour tournaments called "Atomic Revolution" with cash prizes where 8 thousand people participated in the 2022 edition. [10]
It has garnered serious attention from chess grandmasters with Andrew Tang reaching quarterfinals and Jeffery Xiong reaching semifinals of Atomic Chess Championship 2017 hosted on Lichess, where both got knocked out by GM Arka50 who has won the championship in 2017, 2018 and 2020 whereas he did not participate in 2019 and 2021 editions. [11]
The first-move advantage enjoyed by White is much greater in this game than in standard chess. However, no attempts to prove a win for White have been successful.
Material sacrifices are more common in atomic chess than in chess. In the opening and middlegame, it is common to offer a piece in order to open spaces to seize an initiative. [2]
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White has the initiative in atomic chess, and many openings begin with a quick attempt to explode Black's d-, e-, or f-pawns. [12] For this reason, atomic openings are fraught with traps, and Black may have to respond precisely to defend. Several common traps begin with 1.Nf3 followed by Ng5 or Ne5, forcing Black to start with 1..f6 to maintain rough equality. [6] Games between experienced players follow more traditional opening principles, such as piece development , controlling space , and winning material . [12]
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Black is forced to retain the connection, or the queen will chase the king and deliver mate.
As with atomic opening theory, a small amount of endgame theory and analyses have been published online by strong players. [13]
A common scenario in atomic endgames is to have two kings on adjacent squares. As a player cannot intentionally blow up their own king, a king can never capture another piece, including another king. Similarly, because a capture affects all adjacent squares, one king cannot be captured directly if it means destruction of the other. Moving one king towards the other is thus a strategy to achieve a draw. The player with the advantage must then maneuver into a position where a non-king piece can be captured that is adjacent to one king but not the other. If there is no piece that can be captured, the player with the advantage can promote two queens and force the opponent into zugzwang and therefore forcing the opponent's king away from their king. Creative use of zugzwang is a common tactic to force a win in these situations. [14]
The Internet Chess Club variation of atomic chess ignores check completely, and thus leads to different outcomes in certain situations. For example, a king and rook vs. king endgame that would be a draw under normal circumstances can become a forced win on ICC.
Other chess variants based on explosions:
Chess is a board game for two players, called White and Black, each controlling an army of chess pieces, with the objective to checkmate the opponent's king. It is sometimes called international chess or Western chess to distinguish it from related games such as xiangqi and shogi. The recorded history of chess goes back at least to the emergence of a similar game, chaturanga, in seventh century India. The rules of chess as they are known today emerged in Europe at the end of the 15th century, with standardization and universal acceptance by the end of the 19th century. Today, chess is one of the world's most popular games played by millions of people worldwide.
Shogi, also known as Japanese chess, is a strategy board game for two players. It is one of the most popular board games in Japan and is in the same family of games as Western chess, chaturanga, xiangqi, Indian chess, and janggi. Shōgi means general's board game.
Xiangqi, commonly known as Chinese chess or elephant chess, is a strategy board game for two players. It is the most popular board game in China. Xiangqi is in the same family of games as shogi, janggi, Western chess, chaturanga, and Indian chess. Besides China and areas with significant ethnic Chinese communities, this game is also a popular pastime in Vietnam, where it is known as cờ tướng, literally 'General's chess'.
Baroque chess is a chess variant invented in 1962 by Robert Abbott. In 1963, at the suggestion of his publisher, he changed the name to Ultima, by which name it is also known. Abbott later considered his invention flawed and suggested amendments to the rules, but these suggestions have been substantially ignored by the gaming community, which continues to play by the 1962 rules. Since the rules for Baroque were first laid down in 1962, some regional variation has arisen, causing the game to diverge from Ultima.
The king is the most important piece in the game of chess. It may move to any adjoining square; it may also perform, in tandem with the rook, a special move called castling. If a player's king is threatened with capture, it is said to be in check, and the player must remove the threat of capture on their next move. If this cannot be done, the king is said to be in checkmate, resulting in a loss for that player. A player cannot make any move that places their own king in check. Despite this, the king can become a strong offensive piece in the endgame or, rarely, the middlegame.
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.
Losing chess is one of the most popular chess variants. The objective of each player is to lose all of their pieces or be stalemated, that is, a misère version. In some variations, a player may also win by checkmating or by being checkmated.
This glossary of chess explains commonly used terms in chess, in alphabetical order. Some of these terms have their own pages, like fork and pin. For a list of unorthodox chess pieces, see Fairy chess piece; for a list of terms specific to chess problems, see Glossary of chess problems; for a list of named opening lines, see List of chess openings; for a list of chess-related games, see List of chess variants; for a list of terms general to board games, see Glossary of board games.
Zugzwang is a situation found in chess and other turn-based games wherein one player is put at a disadvantage because of their obligation to make a move; a player is said to be "in zugzwang" when any legal move will worsen their position.
Stalemate is a situation in chess where the player whose turn it is to move is not in check and has no legal move. Stalemate results in a draw. During the endgame, stalemate is a resource that can enable the player with the inferior position to draw the game rather than lose. In more complex positions, stalemate is much rarer, usually taking the form of a swindle that succeeds only if the superior side is inattentive. Stalemate is also a common theme in endgame studies and other chess problems.
In chess, a tactic is a sequence of moves that each makes one or more immediate threats – a check, a material threat, a checkmating sequence threat, or the threat of another tactic – that culminates in the opponent's being unable to respond to all of the threats without making some kind of concession. Most often, the immediate benefit takes the form of a material advantage or mating attack; however, some tactics are used for defensive purposes and can salvage material that would otherwise be lost, or to induce stalemate in an otherwise lost position.
Dark chess is a chess variant with incomplete information, similar to Kriegspiel. It was invented by Jens Bæk Nielsen and Torben Osted in 1989. A player does not see the entire board – only their own pieces and the squares that they can legally move to.
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.
Cylinder chess is a chess variant. The game is played as if the board were a cylinder, with the left side of the board joined to the right side. Cylinder chess is one of six chess variants described by the Arabic historian Ali al-Masudi in 947.
Kriegspiel is a chess variant invented by Henry Michael Temple in 1899 and based upon the original Kriegsspiel developed by Georg von Reiswitz in 1812. In this game, each player can see their own pieces but not those of their opponent. For this reason, it is necessary to have a third person act as an umpire, with full information about the progress of the game. Players attempt to move on their turns, and the umpire declares their attempts 'legal' or 'illegal'. If the move is illegal, the player tries again; if it is legal, that move stands. Each player is given information about checks and captures. They may also ask the umpire if there are any legal captures with a pawn. Since the position of the opponent's pieces is unknown, Kriegspiel is a game of imperfect information.
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.
Dice chess can refer to a number of chess variants in which dice are used to alter gameplay; specifically that the moves available to each player are determined by rolling a pair of ordinary six-sided dice. There are many different variations of this form of dice chess. One of them is described here.
The following outline is provided as an overview of and topical guide to chess:
Chess 2: The Sequel is a chess variant created by David Sirlin and Zachary Burns of Ludeme Games. Sirlin, whose previous design work includes rebalancing Super Street Fighter II Turbo HD Remix, approached what he believed to be a problem of rote endgames and static opening games in chess by introducing asymmetrical piece compositions and an additional win condition. A video game version of Chess 2 is available on Ouya as of 2014. The game was released on Steam on 19 August 2014.
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