Fischer random chess
One of 960 possible starting setups. Black's setup always mirrors White's.
|Years active||Since June 19, 1996|
|Genre(s)||Board game |
|Setup time||~1 min + 1 min to determine starting position|
|Playing time||Casual games: 10–60 min|
Tournament games: from 10 min (fast chess) to >6 h
|Random chance||Pieces are randomized|
|Skill(s) required||Strategy, tactics|
Fischer random chess, also known as Chess960, is a variation of the game of chess invented by former world chess champion Bobby Fischer. Fischer announced this new game variation on June 19, 1996, in Buenos Aires, Argentina. Fischer random chess employs the same board and pieces as standard chess, but the starting position of the pieces on the players' is randomized, following certain rules. The random setup makes gaining an advantage through the memorization of openings impracticable; players instead must rely more on their spontaneous talent and creativity over the board.
Randomizing the main pieces had long been known as shuffle chess; however, Fischer random chess introduces new rules regarding the initial random setup, "preserving the dynamic nature of the game by retaining for each player and the right to castle for both sides". The result is 960 unique possible starting positions.
In 2008, FIDE added Chess960 to an appendix of the Laws of Chess. The first world championship officially sanctioned by FIDE, the FIDE World Fischer Random Chess Championship 2019, was held in 2019, bringing more prominence to the variant.
|This article uses algebraic notation to describe chess moves.|
Before the game, a starting position is randomly determined and set up, subject to certain requirements. White's pieces (not pawns) are placed randomly on the first rank, following two rules:
- The bishops must be placed on opposite-color squares.
- The king must be placed on a square between the rooks.
Black's pieces are placed equal-and-opposite to White's pieces. (For example, if the white king is randomly determined to start on f1, then the black king is placed on f8.) Pawns are placed on the players' second as in standard chess.
After setup, the game is played the same as standard chess in all respects, with the exception of castling from the different possible starting positions for king and rooks.
There are 4 × 4 × 6 × 10 × 1 = 960 legal starting positions:
- 4 possible squares for the light-squared bishop;
- 4 possible squares for the dark-squared bishop;
- 6 remaining squares for the queen;
- 10 ways to place the two (identical) knights on the remaining 5 squares;
- 1 way to place the two rooks and king on the remaining 3 squares, since the king must be between the rooks.
This provides an easy way to set up a game (e.g. using a die / re-roll if needed to get values in the range 1–4 or 1–5).
As in standard chess, each player may castle once per game, moving both the king and a rook in a single move; however, the castling rules were reinterpreted in Fischer random chess to support the different possible initial positions of king and rook. After castling, the final positions of king and rook are exactly the same as in standard chess, namely:
- After a-side castling (/long castling in standard chess), the king finishes on the c- and the a-side rook finishes on the d-file. The move is notated 0-0-0 as in standard chess.
- After h-side castling (/short castling in standard chess), the king finishes on the g-file and the h-side rook finishes on the f-file. The move is notated 0-0 as in standard chess.
Castling prerequisites are the same as in standard chess, namely:
- The king and the castling rook must not have previously moved.
- No square from the king's initial square to its final square may be under attack by an enemy piece.
- All the squares between the king's initial and final squares (including the final square), and all the squares between the castling rook's initial and final squares (including the final square), must be vacant except for the king and castling rook.
FIDE's recommended procedure for castling unambiguously is first to move the king outside the playing area next to its final square, then to move the rook to its final square, then to move the king to its final square. Another recommendation is to verbally announce the intent to castle before doing so.
In some starting positions, squares can remain occupied during castling that would be required to be vacant under standard rules. Castling a-side (0-0-0) could still be possible despite the home rank a-, b-, or e-file squares being occupied, and similarly for the e- and h-files for h-side castling (0-0). In other positions, it can happen that the king or rook does not move during the castling maneuver since it already occupies its destination square – e.g., an h-side rook that starts on the f-file; in this case, only the king moves. No initial position would allow a castling where neither piece moves, as the king must start between the rooks.
Another unusual possibility is for castling to be available as the first move of the game, as happened in the 11th game of the tournament match between Hikaru Nakamura and Magnus Carlsen, Fischer Random Blitz 2018. The starting position had kings at f1/f8 and h-side rooks at g1/g8. Both players took the opportunity to castle on the first move (1.0-0 0-0).
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The study of openings in Fischer random chess is in its infancy, but fundamental opening principles still apply, including: protect the king, control the central squares (directly or indirectly), and develop rapidly, starting with the less valuable pieces. Unprotected pawns may also need to be dealt with quickly. The majority of starting positions have unprotected pawns, and some starting positions have up to two that can be attacked on the first move (see diagram). The Stockfish program rates the Fischer random chess opening positions between 0.1 and 0.5 pawns advantage for White, while the mean value for the same in standard chess is 0.2.
It has been argued that two games should be played from each starting position, with players alternating colors, since the advantage offered to White by some initial positions may be greater than in standard chess. For example, in some Fischer random chess starting positions, White can attack an unprotected black pawn on the first move, whereas in standard chess it takes two moves for White to attack, and there are no unprotected pawns.
Fischer random chess is a variant of shuffle chess, which had been suggested as early as 1792 with games played as early as 1842. Fischer's modification "imposes certain restrictions, arguably an improvement on the anarchy of the fully randomized game in which one player is almost certain to start at an advantage". Fischer started to develop his new version of chess after the 1992 return match with Boris Spassky. The result was the formulation of the rules of Fischer random chess in September 1993, introduced formally to the public on June 19, 1996 in Buenos Aires, Argentina.
Fischer's goal was to eliminate what he considered the complete dominance of openings preparation in classical chess, replacing it with creativity and talent. In a situation where the starting position was random it would be impossible to fix every move of the game. Since the "opening book" for 960 possible opening systems would be too difficult to devote to memory, the players must create every move originally. From the first move, both players must devise original strategies and cannot use well-established patterns. Fischer believed that eliminating memorized book moves would level the playing field.
During the summer of 1993, Bobby Fischer visited László Polgár and his family in Hungary. All of the Polgar sisters (Judit Polgár, Susan Polgar, and Sofia Polgar) played many games of Fischer Random chess with Fischer. At one point Sofia beat Fischer three games in a row. Fischer was not pleased when the father, Lazlo, showed Fischer an old chess book that described what appeared to be a forerunner of Fischer Random chess. The book was written by Izidor Gross and published in 1910. Bobby then changed the rules of his variation in order to make it different.
- 1996 – The first Fischer random chess tournament was held in Vojvodina, Yugoslavia in the spring of 1996, and was won by GM Péter Lékó with 9½/11, ahead of GM Stanimir Nikolić with 9 points.
- 2006–present – The first Fischer Random Championships of the Netherlands was held by Fischer Z chess club and has since been held annually. GM Dimitri Reinderman has won this title for three years, champion in 2010, 2014, and 2015. Two grandmasters have won the title twice, GM Yasser Seirawan and Dutch GM Dennis de Vreugt.
- 2010 – In 2010 the US Chess Federation sponsored its first Chess960 tournament, at the Jerry Hanken Memorial US Open tournament in Irvine, California. This one-day event, directed by Damian Nash, saw a first place tie between GM Larry Kaufman and FM Mark Duckworth.
- 2012 – The British Chess960 Championship was held at the Mind Sports Olympiad, won by Ankush Khandelwal.
- 2018 – The first edition of the European Fischer Random Cup was held in Reykjavik on 9 March 2018, on Fischer's 75th birthday. It was won by Aleksandr Lenderman.
- 2019 – The Icelandic Chess Federation organized the European Fischer Random Championship on the rest day of 34th edition of The GAMMA Reykjavik Open on 12 April 2019. The tournament was won by the then 15-year-old Iranian prodigy Alireza Firouzja, a full point ahead of US's Andrew Tang, who was second on tiebreaks.
- 2019 - The FIDE World Fischer Random Chess Championship 2019 started on April 28, 2019, with the first qualifying tournaments, which took place online and were open to all interested participants. After several rounds, finalists Wesley So and Magnus Carlsen played for the crown. The official FRC Champion was Wesley So 
Note: None of the Mainz championships were recognized by FIDE. Furthermore, they were all played with rapid time controls.
- 2001 – In 2001, Lékó became the first Fischer random chess world champion, defeating GM Michael Adams in an eight-game match played as part of the Mainz Chess Classic. There were no qualifying matches (also true of the first standard chess world chess champion titleholders), but both players were in the top five in the January 2001 world rankings for standard chess. Lékó was chosen because of the many novelties he has introduced to known chess theories, as well as his previous tournament win; in addition, Lékó has supposedly played Fischer random chess games with Fischer himself. Adams was chosen because he was the world number one in blitz (rapid) chess and is regarded as an extremely strong player in unfamiliar positions. The match was won by a narrow margin, 4½ to 3½.
- 2002 – In 2002 at Mainz, an open tournament was held which was attended by 131 players, with Peter Svidler taking first place. Fischer random chess was selected as the April 2002 "Recognized Variant of the Month" by The Chess Variant Pages (ChessVariants.org). The book Shall We Play Fischerandom Chess? was published in 2002, authored by Yugoslavian GM Svetozar Gligorić.
- 2003 – At the 2003 Mainz Chess Classic, Svidler beat Lékó in an eight-game match for the World Championship title by a score of 4½–3½. The Chess960 open tournament drew 179 players, including 50 GMs. It was won by Levon Aronian, the 2002 World Junior Champion. Svidler is the official first World New Chess Association (WNCA) world champion inaugurated on August 14, 2003 with Jens Beutel, Mayor of Mainz as the President and Hans-Walter Schmitt, Chess Classic organiser as Secretary. The WNCA maintains an own dedicated Chess960 rating list.
- 2004 – Aronian played Svidler for the title at the 2004 Mainz Chess Classic, losing 4½–3½. At the same tournament in 2004, Aronian played two Chess960 games against the Dutch computer chess program The Baron, developed by Richard Pijl. Both games ended in a draw. It was the first ever man against machine match in Chess960. Zoltán Almási won the Chess960 open tournament in 2004.
- 2005 – Almási and Svidler played an eight-game match at the 2005 Mainz Chess Classic. Once again, Svidler defended his title, winning 5–3. Levon Aronian won the Chess960 open tournament in 2005. During the Chess Classic 2005 in Mainz, initiated by Mark Vogelgesang and Eric van Reem, the first-ever Chess960 computer chess world championship was played. Nineteen programs, including the powerful Shredder, played in this tournament. As a result of this tournament, Spike became the first Chess960 computer world champion.
- 2006 – The 2006 Mainz Chess Classic saw Svidler defending his championship in a rematch against Levon Aronian. This time, Aronian won the match 5–3 to become the third ever Fischer random chess world champion. Étienne Bacrot won the Chess960 open tournament, earning him a title match against Aronian in 2007. In 2006, Shredder won the computer championship, making it Chess960 computer world champion. Three new Chess960 world championship matches were held, in the women, junior and senior categories. In the women category, Alexandra Kosteniuk became the first Chess960 Women World Champion by beating Elisabeth Pähtz 5½ to 2½. The 2006 Senior Chess960 World Champion was Vlastimil Hort, and the 2006 Junior Chess960 World Champion was Pentala Harikrishna.
- 2007 – In 2007 Mainz Chess Classic Aronian successfully defended his title of Chess960 World Champion over Viswanathan Anand, while Victor Bologan won the Chess960 open tournament. Rybka won the 2007 computer championship.
- 2008 – Hikaru Nakamura won the 2008 Finet Chess960 Open (Mainz).
- 2009 – The last Mainz tournament was held in 2009. Hikaru Nakamura won the Chess960 World Championship against Aronian, while Alexander Grischuk won the Chess960 open tournament.
|Year||Championship||Open||Women's Championship||Computer Championship|
|2001||Péter Lékó (4½–3½ vs. Michael Adams)|
|2003||Peter Svidler (4½–3½ vs. Péter Lékó)||Levon Aronian|
|2004||Peter Svidler (4½–3½ vs. Levon Aronian)||Zoltán Almási|
|2005||Peter Svidler (5–3 vs. Zoltán Almási)||Levon Aronian||Spike|
|2006||Levon Aronian (5–3 vs. Peter Svidler)||Étienne Bacrot||Alexandra Kosteniuk (5½–2½ vs. Elisabeth Pähtz)||Shredder|
|2007||Levon Aronian (2–2, 1½–½ vs. Viswanathan Anand)||Victor Bologan||Rybka|
|2008||Hikaru Nakamura||Alexandra Kosteniuk (2½–1½ vs. Kateryna Lahno)||Rybka|
|2009||Hikaru Nakamura (3½–½ vs. Levon Aronian)||Alexander Grischuk||Rybka|
In 2005, chess program The Baron played two Fischer random chess games against Chess960 World Champion Peter Svidler, who won 1½–½. The chess program Shredder, developed by Stefan Meyer-Kahlen of Germany, played two games against Zoltán Almási from Hungary, where Shredder won 2–0.
In 2018, a Fischer random chess match between reigning classical World Chess Champion Magnus Carlsen and the unofficial Fischer random chess world champion Hikaru Nakamura was held in Oslo, Norway. The match consisted of 8 rapid and 8 blitz games, with the rapid games counting double. Each position was used in two games, with colors reversed. Carlsen prevailed with a score of 14–10.
From 11 to 14 September 2018, the Saint Louis Chess Club held a Fischer random chess event. The playing format included five individual matches, each pair of players facing the same five different starting positions, with 6 rapid games (counting 2 points each) and 14 blitz games (counting 1 point each). The players and scores: Veselin Topalov (14½–11½) defeated Garry Kasparov; Hikaru Nakamura (14–12) defeated Peter Svidler; Wesley So (14½–11½) defeated Anish Giri; Maxime Vachier-Lagrave (17½–8½) defeated Sam Shankland; Levon Aronian (17½–8½) defeated Leinier Dominguez.
The first world championship in Fischer random chess officially recognized by FIDE were announced April 20, 2019, and ended on November 2, 2019. Wesley So defeated Magnus Carlsen 13.5–2.5 in the last round, and became the first world champion in Fischer Random Chess.
During the announcement FIDE president Arkady Dvorkovich commented: "It is an unprecedented move that the International Chess Federation recognizes a new variety of chess, so this was a decision that required to be carefully thought out. But we believe that Fischer Random is a positive innovation: It injects new energies and enthusiasm into our game, but at the same time it doesn't mean a rupture with our classical chess and its tradition. It is probably for this reason that Fischer Random chess has won the favor of the chess community, including the top players and the world champion himself. FIDE couldn't be oblivious to that: It was time to embrace and incorporate this modality of chess." 
The variant has held a number of different names. It was originally known as "Fischerandom", the name given by Fischer. Fischer random chess is the official term, used by FIDE.
Hans-Walter Schmitt, chairman of the Frankfurt Chess Tigers e.V. and an advocate of the variant, started a brainstorming process for creating a new name, which had to meet the requirements of leading grandmasters; specifically, the new name and its parts:
- should not contain part of the name of any grandmaster;
- should not include negatively biased or "spongy" elements (such as "random" or "freestyle"); and
- should be universally understood.
The effort culminated in the name choice "Chess960" – derived from the number of different possible starting positions. Fischer never publicly expressed an opinion on the name "Chess960".
Reinhard Scharnagl, another proponent of the variant, advocated the term "FullChess". Today he uses FullChess, however, to refer to variants which consistently embed standard chess (e.g. Chess960, and some new variants based on the extended 10×8 piece set in Capablanca Chess). He recommends the name Chess960 for the variant in preference to Fischer random chess.
Coding games and positions
Recorded games must convey the Fischer random chess starting position. Games recorded using the Portable Game Notation (PGN) can record the initial position using Forsyth–Edwards Notation (FEN), as the value of the "FEN" tag. Castling is notated the same as in standard chess (except PGN requires letter O not number 0). Note that not all chess programs can handle castling correctly in Fischer random chess games. To correctly record a Fischer random chess game in PGN, an additional "Variant" tag (not "Variation" tag, which has a different meaning) must be used to identify the rules; the rule named "Fischerandom" is accepted by many chess programs as identifying Fischer random chess, though "Chess960" should be accepted as well. This means that in a PGN-recorded game, one of the PGN tags (after the initial seven tags) would look like this: [Variant "Fischerandom"].
FEN is capable of expressing all possible starting positions of Fischer random chess; however, unmodified FEN cannot express all possible positions of a Chess960 game. In a game, a rook may move into the back row on the same side of the king as the other rook, or pawn(s) may be underpromoted into rook(s) and moved into the back row. If a rook is unmoved and can still castle, yet there is more than one rook on that side, FEN notation as traditionally interpreted is ambiguous. This is because FEN records that castling is possible on that side, but not which rook is still allowed to castle.
A modification of FEN, X-FEN, has been devised by Reinhard Scharnagl to remove this ambiguity. In X-FEN, the castling markings "KQkq" have their expected meanings: "Q" and "q" mean a-side castling is still legal (for White and Black respectively), and "K" and "k" mean h-side castling is still legal (for White and Black respectively). However, if there is more than one rook on the baseline on the same side of the king, and the rook that can castle is not the outermost rook on that side, then the file letter (uppercase for White) of the rook that can castle is used instead of "K", "k", "Q", or "q"; in X-FEN notation, castling potentials belong to the outermost rooks by default. The maximum length of the castling value is still four characters. X-FEN is upwardly compatible with FEN, that is, a program supporting X-FEN will automatically use the normal FEN codes for a traditional chess starting position without requiring any special programming. As a benefit all 18 pseudo FRC positions (positions with traditional placements of rooks and king) still remain uniquely encoded.
The solution implemented by chess engines like Shredder and Fritz is to use the letters of the columns on which the rooks began the game. This scheme is sometimes called Shredder-FEN. For the traditional setup, Shredder-FEN would use HAha instead of KQkq.
Views of grandmasters
Fischer's proposed "new chess" has elicited various comments from grandmasters.
- "Of course, if people do not want to do any work then it is better to start the game from a random position." — Garry Kasparov, December 2001
- "Random chess lets me enjoy myself and get publicity for chess without having to disrupt my life for months of preparation." — Garry Kasparov, August 2018
- "I think we’re making theory or even making history because we’re opening not even a new chapter but basically a new book on the game of chess. That’s why I think all players are excited." — Garry Kasparov, September 2018
- "To me, mainly chess is art — that's why I like Fischer Random a lot; there is a lot of creativity." — Wesley So, November 2019
- "I have to say that I love Chess960! I like to be creative and I really enjoy the Chess960 events in Mainz." — Alexandra Kosteniuk, August 2010
- "I don't see any drawbacks in Fischer Random chess. The only slight shortcoming is the start position, otherwise there are just advantages. That's why I support it in full. If all the chess professionals played Fischer Random, our game could have been much more popular." — Alexander Grischuk, March 2018 [translated from Russian]
- "Chess is already complicated enough." — Vassily Ivanchuk
- "It’s a game I really love and I see it as the future of chess." — Levon Aronian, July 2011
- "I think chess960 is great as it is simply pure intuition and understanding without theory or computers" — Hikaru Nakamura, February 2014
- "Personally, It is refreshing to watch the Chess960 match between Carlsen and Nakamura. As a chess player and a fan, this is an exciting change. Could this be the future?" — Vidit Gujrathi, February 2018
- "No more theory means more creativity." — Artur Yusupov
- "[...] the play is much improved over traditional chess because you don't need to analyze or memorize any book openings. Therefore, your play becomes truly creative and real." — Svetozar Gligorić
- "Finally, one is no longer obliged to spend the whole night long troubling oneself with the next opponent's opening moves. The best preparation consists just of sleeping well!" — Péter Lékó
- "I tried many different starting positions and all these were somehow very unharmonious. And this is not surprising as in many of these positions there is immediate forced play: the pieces are placed so badly at the start that there is a need to improve their positions in one way only, which decreases the number of choices." — Vladimir Kramnik [translated from Russian]
- "Fischer Random is an interesting format, but it has its drawbacks. In particular, the nontraditional starting positions make it difficult for many amateurs to enjoy the game until more familiar positions are achieved. The same is true for world-class players, as many have confessed to me privately. Finally, it also seems to lack an aesthetic quality found in traditional chess, which makes it less appealing for both players and viewers, even if it does occasionally result in an exciting game." — Vladimir Kramnik
- "Both players have bad positions." — Helmut Pfleger,, commentating on Lékó–Adams, Mainz 2001, game 4
- "The changes in chess concern the perfection of computers and the breakthrough of high technology. Under this influence the game is losing its charm and reducing more and more the number of creative players. [...] I am a great advocate of Fischer's idea of completely changing the rules of chess, of creating a practically new game. It is the only way out, because then there would be no previous experience on which a machine could be programmed, at least until this new chess itself becomes exhausted. Fischer is a genius and I believe that his project would save the game." — Ljubomir Ljubojević
- "In my opinion, we should start moving towards Chess960, just like we started to generate energy with renewable energy sources a while ago. If we start now, then by the time it reaches a crisis point, we will have a viable alternative ready." — Srinath Narayanan, August 2017
Comments by Fischer
- "Teach people to play new chess, right away. Why do you offer them a black and white television set, when there is a set in color?" — Fischer, in the only meeting with FIDE President Kirsan Ilyumzhinov, responding to the latter advocating "step by step" changes mindful of the heritage of chess
- "I don't know when, but I think we are approaching that [the end of chess] very rapidly. I think we need a change in the rules of chess. For example, I think it would be a good idea to shuffle the first row of the pieces by computer ... and this way you will get rid of all the theory. One reason that computers are strong in chess is that they have access to enormous theory [...] I think if you can turn off the computer's book, which I've done when I've played the computer, they are still rather weak, at least at the opening part of the game, so I think this would be a good improvement, and also just for humans. It is much better, I think, because chess is becoming more and more simply memorization, because the power of memorization is so tremendous in chess now. Theory is so advanced, it used to be theory to maybe 10 or 15 moves, 18 moves; now, theory is going to 30 moves, 40 moves. I think I saw one game in Informator, the Yugoslav chess publication, where they give an N [theoretical novelty] to a new move, and I recall this new move was around move 50. [...] I think it is true, we are coming to the end of the history of chess with the present rules, but I don't say we have to do away with the present rules. I mean, people can still play, but I think it's time for those who want to start playing on new rules that I think are better." — Fischer (September 1, 1992)
The initial setup need not necessarily be random. The players or a tournament setting may decide on a specific position in advance, for example. Tournament Directors prefer that all boards in a single round play the same random position, as to maintain order and abbreviate the setup time for each round.
Edward Northam suggests the following approach for allowing players to jointly create a position without randomizing tools: First, the back ranks are cleared of pieces, and the white bishops, knights, and queen are gathered together. Starting with Black, the players, in turn, place one of these pieces on White's back rank, where it must stay. The only restriction is that the bishops must go on opposite-color squares. There will be a vacant square of the required color for the second bishop, no matter where the previous pieces have been placed. Some variety could be introduced into this process by allowing each player to exercise a one-time option of moving a piece already on the board instead of putting a new piece on the board. After all five pieces have been put on the board, the king must be placed on the middle of the three vacant back rank squares that remain. Rooks go on the other two.
This approach to the opening setup has much in common with Pre-Chess, the variant in which White and Black, alternately and independently, fill in their respective back ranks. Pre-Chess could be played with the additional requirement of ending up with a legal Fischer random chess opening position. A chess clock could even be used during this phase as well as during normal play.
Without some limitation on which pieces go on the board first, it is possible to reach impasse positions, which cannot be completed to legal Fischer random chess starting positions. Example: Q.RB.N.N If the players want to work with all eight pieces, they must have a prior agreement about how to correct illegal opening positions that may arise. If the bishops end up on same color squares, a simple action, such as moving the a-side bishop one square toward the h-file, might be agreeable, since there is no question of preserving randomness. Once the bishops are on opposite-color squares, if the king is not between the rooks, it should trade places with the nearest rook.
In "Castling in Chess960: An appeal for simplicity", John Kipling Lewis proposes alternative castling rules which Lewis has named "Orthodoxed Castling". The preconditions for castling are the same as in Chess960, but when castling,
[...] the king is transferred from its original square two squares towards (or over) the rook, then that rook is transferred to the square the king has just crossed (if it is not already there). If the king and rook are adjacent in a corner and the king cannot move two spaces over the rook, then the king and rook exchange squares.
Unlike Fischer random chess, the final position after castling in Chess480 will usually not be the same as the final position of a castling move in traditional chess. Lewis argues that this alternative better conforms to how the castling move was historically developed.
Lewis has named this chess variation "Chess480"; it follows the rules of Chess960 with the exception of the castling rules. Although a Chess480 game can start with any of 960 starting positions, the castling rules are symmetrical (whereas the Chess960 castling rules are not), so that mirror-image positions have identical strategies; thus there are only 480 effectively different positions. The number of starting positions could be reduced to 480 without losing any possibilities, for example by requiring the white king to start on a light (or dark) square.
There are other claims to the nomenclature "Chess480"; Reinhard Scharnagl defines it as the white queen is always to the left of the white king.
David O'Shaughnessy argues in "Castling in Chess480: An appeal for sanity" that the Chess480 rules are often not useful from a gameplay perspective. In about 66% of starting positions, players have the options of castling deeper into the wing the king started on, or castling into the center of the board (when the king starts on the b-, c-, f-, or g-files). From Wikipedia article Castling: "Castling is an important goal in the early part of a game, because it serves two valuable purposes: it moves the king into a safer position away from the center of the board, and it moves the rook to a more active position in the center of the board." An example of poor castling options is a position where the kings start on g1 and g8 respectively. There will be no possibility of "opposite-side castling" where each player's pawns are free to be used in , as the kings' scope for movement is very restricted (it can only move to the h- or e-file). These "problem positions" play well with Chess960 castling rules.
There are several other variants based on randomization of the initial setup. "Randomized Chess, in one or other of its many reincarnations, continues to attract support even, or perhaps especially, that of top players."
- Double Fischer random chess: The same as Fischer random chess, except the White and Black starting positions do not mirror each other.
- Transcendental chess (or TC): The same as double Fischer random, minus the restriction that the king is between rooks, and there is no castling. The variation Auction TC introduces the concept of auction (offering extra moves for the right of picking the side). By Maxwell Lawrence (1978).
- Shuffle chess: The parent variant of Fischer random chess. There are no restrictions on the back-rank shuffles, with castling possible only when king and rook are on their traditional starting squares.
- "It was the world chess champion Robert James Fischer who, in 1996, formulated precise rules for randomized chess [...]. Though still not so well-known, this invention of Bobby Fischer is already raising reasonable hopes among experts that chess will remain a mass game for the foreseeable future." (Gligorić 2002:5). "Despite his extremely long absence from competition, [Fischer] won [the 1992 return match with Spassky] with a good score of 10–5 in decisive games. It was then that Fischer began to think of reforming the game. The result of his hard work over several years is Fischerandom Chess—and plans for exhibition matches of a new kind..." (Gligorić 2002:8)
- Eric van Reem. "The birth of Fischer Random Chess". The Chess Variant Pages. Retrieved January 4, 2016.
- Gligorić (2002), p. 9.
- Bobby Fischer makes his move in Argentina at the Wayback Machine (archived January 23, 2004)
- Gligorić (2002), p. 40.
- From laws history page of the CCA "FIDE Laws of Chess - coming into force on 1 July 2009" (PDF). CCA - Chess Arbiters’ Association. Retrieved July 5, 2020.
- "Fide Laws of Chess taking effect from 1 January 2018". FIDE.
- In 2008 FIDE added Chess960 rules to an appendix of the Handbook. This section is now classified under "Guidelines", indicating that the rules presented do not have the weight of FIDE law.
- "The World Fischer Random Chess Championship is now officially recognized by FIDE". FIDE. Retrieved October 28, 2019.
- "Fischer Random Chess (Chess960)". www.dwheeler.com.
- "Carlsen adds a new title: Chess960 champion". ChessBase. February 14, 2018.
- Friedel, Frederic (February 28, 2018). "The problem with Chess960". Chess News. Retrieved March 2, 2018.
- Gligorić (2002), p. 36.
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