Losing chess

Losing chess (also known as antichess, the losing game, giveaway chess, suicide chess, killer chess, must-kill, take-all chess, capture chess or losums) is one of the most popular chess variants.[1][2] 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.

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After 1.e3 b5 2.Bxb5 Bb7 (diagram) White must capture 3.Bxd7, the only legal move. Then Black must also capture, but can choose among Nxd7, Qxd7, Kxd7, or Bxg2.


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 king has no royal power and accordingly:
    • it may be captured as any other piece;
    • there is no check or checkmate;
      • therefore the king may expose itself to capture;
    • there is no castling;
    • a pawn may also promote to a king.
  • Stalemate is a win for the stalemated player (the player with no legal moves).

A player wins by being unable to make a move (which includes having no remaining pieces on the board). Apart from move repetition, draw by agreement, and the fifty-move rule, the game is also drawn when neither player can win (for example, when the only pieces remaining are bishops of opposite colors).

History

The origin of the game is unknown, but believed to significantly predate an early version, named take me, played in the 1870s.[3] Because of the popularity of losing chess, several variations have spawned. The most widely played (main variant) 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.[4] 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.[4] On this site, players from all over the world play losing chess every day (thousands of games per day), tournaments with different time controls are held (dozens of tournaments per day), there are specialized bots,[5] and the variant itself is the most popular (except for regular chess) in terms of the number of games played.[6] 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 (as of the end of 2019).[6]

Analysis
1.d3?? is one of several openings that lose by force: 1.d3 g5 2.Bxg5 Bg7 3.Bxe7 Bxb2 4.Bxd8 Bxa1 5.Bxc7 Bc3 6.Bxb8 Rxb8 7.Nxc3 d5 8.Nxd5 Nf6 9.Nxf6 Rg8 10.Nxe8 Rxg2 11.Bxg2 f6 12.Bxb7 Rxb7 13.Nxf6 h5 14.Nxh5 Rb1 15.Qxb1 Bb7 16.Qxb7 a6 17.Qxa6 0–1

Because of the forced capture rule, losing chess games often involve long sequences of forced 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.[lower-alpha 1]

This main variant of losing chess was weakly solved in October 2016; White is able to force a win beginning with 1.e3.[lower-alpha 2] Some lines are trivial (1…d5, 1…d6, 1…Na6, and 1…g6 lose in less than 20 moves), others are quite simple (1…Nf6, 1…h6, 1…e5, 1…f5, 1…h5, 1…a6, 1…f6, 1…a5 lose in less than 30 moves, subject to knowledge of the theory[7]), some are quite complicated (1…c6, 1…Nh6, 1…Nc6, the win in which may require about 100 moves[8]). The most difficult are the following five openings (in order of increasing difficulty): 1.e3 e6 - (Modern Defence), 1.e3 g5 (Wild Boar Defence), 1.e3 b5 (Classical Defence), 1.e3 c5 (Polish Defence), and 1.e3 b6 (Liardet Defense).

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.[9] 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.[10][11] 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.

Variations

Variations regarding stalemate
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White to move, but there are no legal moves. The position is stalemate. The game result depends on the variant being played.

Implementations of the main variant can vary in regard to stalemate.[12] "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 (the piece types are irrelevant). "Joint" FICS/International rules resolves stalemate as a draw unless it is a victory for the same player under both rulesets.[lower-alpha 2] 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.[13]

Variant 2

Rules are the same as the main rules, except:

  • Pawns promote only to queens.
  • Stalemate is a draw.

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.

Notes
  1. Solutions by David Bronstein were published in Popular Chess Variants (2000), pp. 33–34:
    • 1.d4?? e5 2.dxe5 Qg5 3.Qxd7 Bxd7 4.Bxg5 Kd8 5.Bxd8 a6 6.Bxc7 Ra7 7.Bxb8 b6 8.Bxa7 a5 9.Bxb6 g6 10.Bxa5 Bb4 11.Bxb4 Ne7 12.Bxe7 Rf8 13.Bxf8 h6 14.Bxh6 g5 15.Bxg5 f6 16.Bxf6 Bh3 17.Nxh3 0–1
    • 1.d3?? g5 2.Bxg5 Bg7 3.Bxe7 Bxb2 4.Bxd8 Bxa1 5.Bxc7 Bc3 6.Bxb8 Rxb8 7.Nxc3 d5 8.Nxd5 Nf6 9.Nxf6 Rg8 10.Nxe8 Rxg2 11.Bxg2 f6 12.Bxb7 Rxb7 13.Nxf6 Rb8 14.Nxh7 Rb1 15.Qxb1 Bb7 16.Qxb7 a6 17.Qxa6 0–1
    • 1.e4?? b5 2.Bxb5 Nf6 3.Bxd7 Nxe4 and White loses no matter which capture he chooses:
      • 4.Bxe8 Qxd2 5.Qxd2 (if 5.Bxf7 Qxc1 6.Qxc1 Nxf2 7.Kxf2 Rg8 etc.) 5...Nxd2 6.Kxd2 Rg8 7.Bxf7 c5 8.Bxg8 g6 9.Bxh7 e5 10.Bxg6 e4 11.Bxe4 Nc6 12.Bxc6 Bb7 13.Bxb7 Rc8 14.Bxc8 a6 15.Bxa6 c4 16.Bxc4 Ba3 17.Nxa3 0–1
      • Or 4.Bxc8 Nxd2 5.Bxd2 Qxd2 6.Qxd2 Na6 7.Bxa6 Rc8 8.Bxc8 f5 9.Bxf5 Rg8 10.Bxh7 c5 11.Bxg8 e6 12.Bxe6 c4 13.Bxc4 a6 14.Bxa6 g5 15.Qxg5 Kd8 16.Qxd8 Be7 17.Qxe7 0–1
  2. Watkins, Mark. "Losing Chess: 1. e3 wins for White" (PDF). Retrieved 29 August 2017. - This solution is valid for both FICS and "International" rules on stalemate.
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gollark: I don't *think* those are too common, but just put them in a robust container when you're sending them up.

References
  1. Pritchard (2007), p. 86
  2. Parlett (1999), p. 324
  3. Verney, Major George Hope (1885). Chess Eccentricities. London: Longman, Green, & Co. p. 191.
  4. Andrejić, Vladica (2018). The Ultimate Guide to Antichess. Belgrade: JP “Službeni glasnik”. ISBN 978-86-7297-096-8.
  5. "Antichess bot".
  6. "Lichess.org Game Database".
  7. "Antichess Solution Browser".
  8. "Mark Watkins's Solution Browser".
  9. Pritchard (2000), p. 34
  10. Beasley, John (2000). "A first survey of Losing Chess endgame material published up to the end of 1999" (PDF). The John and Sue Beasley WebSite.
  11. Beasley, John (1999). "Three-man pawnless endings in Losing Chess" (PDF). The John and Sue Beasley WebSite.
  12. Bodlaender, Hans. "Losing Chess". The Chess Variant Pages. Retrieved 25 January 2016.
  13. Pritchard (1994), p. 176

Bibliography

  • Verney, M. G. H. (1885). Chess Eccentricities. London: Longman, Green, & Co. p. 191.
  • Pritchard, D. B. (1994). "Losing Chess". The Encyclopedia of Chess Variants. Games & Puzzles Publications. pp. 176–79. ISBN 0-9524142-0-1.
  • Parlett, David (1999). The Oxford History of Board Games. Oxford University Press Inc. ISBN 0-19-212998-8.
  • Pritchard, D. B. (2000). "§7 Losing Chess". Popular Chess Variants. B.T. Batsford Ltd. pp. 32–38. ISBN 0-7134-8578-7.
  • Pritchard, D. B. (2007). "§10.9 Playing to lose". In Beasley, John (ed.). The Classified Encyclopedia of Chess Variants. John Beasley. pp. 85–89. ISBN 978-0-9555168-0-1.
  • Andrejić, Vladica (2018). The Ultimate Guide to Antichess. Belgrade: JP “Službeni Glasnik”. ISBN 978-86-7297-096-8
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