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.
Rules (main variant)
The rules are the same as those for standard chess, except for the following special rules:
Capturing is compulsory.
When more than one capture is available, the player may choose.
The origin of the game is unknown, but believed to significantly predate an early version, named take me, played in the 1870s. Because of the popularity of losing chess, several variations have spawned. The most widely played is described in Popular Chess Variants by D. B. Pritchard. Losing chess began to gain popularity in the 20th century, which was facilitated by some publications about this variant in the UK, Germany, and Italy. Nevertheless, basically it was the competition at the amateur level, without a well-developed theory. Losing chess gained a new surge in popularity at the turn of the 20th and 21st centuries as an online game, thanks to the implementation of this variant on FICS in 1996, which greatly contributed to the popularization of losing chess. At that time, numerous engines were being developed, endgame tablebases were being created, materials on strategy were being published, and the opening theory was being developed. Currently, most losing chess games are played on Lichess. On this site, players from all over the world play losing chess every day, tournaments with different time controls are held, there are specialized bots, and the variant itself is the most popular in terms of the number of games played. In recent years, Lichess has also been the venue for the Losing Chess World Championships. On average, 150,000 games of losing chess are played on Lichess each month.
Analysis
Because of the forced capture rule, losing chess games often involve long sequences of captures by one player. This means that a minor mistake can doom a game. Such mistakes can be made from the very first move—losing openings for White include 1.a3, 1.b4, 1.c3, 1.d3, 1.d4, 1.e4, 1.f3, 1.f4, 1.h3, 1.h4, 1.Nc3, and 1.Nf3. Some of these openings took months of computer time to solve, but wins against 1.e4, 1.d4, and 1.d3 consist of simple series of forced captures and can be played from memory by most experienced players. This main variant of losing chess was weakly solved in October 2016; White is able to force a win beginning with 1.e3. Some lines are trivial, others are quite simple, some are quite complicated. The most difficult are the following five openings : 1.e3 e6 -, 1.e3 g5, 1.e3 b5, 1.e3 c5, and 1.e3 b6. David Pritchard, the author of The Encyclopedia of Chess Variants, wrote that the "complexity and beauty" of losing chess is found in its endgame. He noted that, in contrast with regular chess, losing chess endgames with just two pieces require considerable skill to play correctly, whereas three- or four-pieces endgames can exceed human capacity to solve precisely. For example, the following endgames may turn out to be quite complicated: 2 Knights vs Rook, 3 Kings vs King, or Bishop+Knight+King vs King. In the latter case, in particular, a win may require more than 60 moves, which means that it is sometimes unattainable due to the fifty-move rule.
Implementations of the main variant can vary in regard to stalemate. "International" rules are as described above, with the stalemated player winning even if that player still has pieces on the board. FICS rules resolve stalemate as a win for the player with the fewer number of pieces remaining; if both have the same number, it is a draw. "Joint" FICS/International rules resolves stalemate as a draw unless it is a victory for the same player under both rulesets. The stalemate in the diagram is a win for White under "International" rules, a win for Black under FICS rules, and a draw under "joint" rules.
Variants in ''The Encyclopedia of Chess Variants''
Pritchard discusses the following variants of the game in The Encyclopedia of Chess Variants. Variant 2 Rules are the same as the main rules, except: Variant 3 Rules are the same as the main rules, except:
The king has royal powers, and removing the king from check takes precedence over capturing another piece.
A player wins by reducing his pieces to a bare king, or by checkmating the opponent.
Stalemate is a draw.
Variant 4 Rules are the same as variant 3, except:
A player wins by reducing his pieces to a bare king, or by getting checkmated.
