Leo Hovestadt

Raindrop Chess Chess as a skill game has one big disadvantage, playing strength can differ considerable, and there is hardly a chance for a much weaker player to win. Raindrop chess introduces that chance factor by the drawing of the cards which determine the move without spoiling the skill factor.

Raindrop chess is surprisingly enjoyable. Unlike earlier attempts with dice or cards to introduce the chance factor, Raindrop chess gives an elegant feeling. For stronger players tatics, strategy and calculation still play an important role. The weaker player always can have the lucky draw of cards and then still winning the game.

Raindrop chess was introduced in 2009 in the Netherlands. The game begins with an empty board, the chessmen waiting on marked areas next to the board.

One by one they appear on the board. Enhanced with a chance factor, this game had been made accessible to anyone familiar with the basic laws of chess. Knowledge of these laws can be easily acquired, should you not be familiar with them just yet. Explanation At the start of the game, all squares on the chess board may be occupied freely. White is first to draw a card. The chessman displayed on that card may now be placed anywhere on the board. The players draw a card in turn. Drawn cards are put aside and made into a pile with displayed pictures upwards.

   King, Queen, Rook, Bishop and Knight: may be placed on any desired, empty square.
   Bishops: a White or Black diamond indicates whether it is a White- or Black-squared Bishop.
   King: cannot be positioned on a square that would put it into check.
   White pawns: can only be placed on rows 2 through 6.
   Black pawns: can only be placed on rows 7 through 3. 

Raindropchess differentiates between ‘Raindrop moves’ and (ordinary) ‘chess moves’. Chess moves are only permitted when a player’s own King has been placed on the board. That player will hence have a choice: make a raindrop move or a chess move (with a chessman that is already on the board). Pawns may move forward to the 8th rank (e.g. for White from the 6th row in two moves) in order to earn promotion. There are only (a maximum of) 4 promotion chess pieces per player available. Chessmen go in exactly the same manner across the board as in international chess, and a player must always get his King out of check during the next move. Captured chessmen stop participating in the game.

Is Raindropchess the future? One night in 2009 at the Dutch family Hillenkamp the chessboard fell on the ground. Using quickly improvised cut paper cards, the pieces were placed back like raindrops on an empty chessboard. Raindropchess was born introducing a chance factor to chess. What is Raindropchess? Raindropchess starts with an empty chessboard, and pieces are dropped anywhere on the chessboard, based on 1 of 16 cards drawn per color. The pawns can only be placed from the 2nd to the 6th row (for white). Once the king is placed, the player can choose between a move or the drawing of a card. A check should always be lifted, otherwise the game is lost. During the development of Raindropchess it was not tried to change chess, but to add a chance factor to it using cards. This chance factor is a nice new element for chess players, but a fun factor for beginners. Kids find Raindropchess easy, since recognizing the picture from a card and then placing the piece on the chessboard is something everyone can do. Surprisingly Raindropchess has almost the same amount of rules as chess, but is not perceived as difficult, since the consequences of good or lucky decisions are much quicker to see. Chess the strategy game for centuries challenging the brightest minds on the world, has now a more dynamic counterpart with a chance factor. Chess is good for the school results of kids, and is therefore used as educational tool. However it requires motivated teachers who have mastered chess, significantly slowing down the introduction of chess on schools. Raindropchess on the contrary may involve the whole school without additional effort of the teachers, since kids learn each other the rules of the game. Kids gather around a board where Raindropchess is played, and the cards cause that kids themselves figure out the rules of the game. Kids of different playing strength also enjoy playing each other, because of the chance factor introduced by the cards. Raindropchess is self-correcting, good for the concentration, promotes analytical thinking and planning and improves calculating abilities. Raindropchess is usually quick, so short games at school can be played during breaks. Raindropchess is now a "proven" chess variant appealing most kids. Its flexibility causes that it can be used in many school situations. About every 500 years chess is changed to cope with new circumstances. Chess came to Europe around 1000, when the checkerboard and the queen was introduced. Circa 1500 in the renaissance the activity range of the queen and bishop move were extended, adapting chess to more dynamic times. Around 2000 through the introduction of internet and game computers like the Nintendo, kids could determine themselves what they liked and learned. Chess too complicated for self learning was quickly losing ground. Although chess was more and more recognized as a learning aid, only waiting for a variation what kids can learn themselves. Raindropchess is fulfilling that promise, proving to be a good chess candidate for the future!

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One of 960 possible starting positions

Chess960 (or Fischer Random Chess) is a chess variant invented and advocated by former World Chess Champion Bobby Fischer, originally announced on June 19, 1996 in Buenos Aires, Argentina. It employs the same board and pieces as standard chess, but the starting position of the main pieces is determined randomly. The random setup forces players to resort to talent and creativity rather than the possibility of obtaining an advantage through the memorization of opening moves.

Randomizing the main pieces has long been known as Shuffle Chess, but Chess960 introduces new rules so that full castling options are retained in all starting positions, resulting in 960 possible (non-mirrored) positions. To maintain the character of standard chess, a player's bishops must start on opposite-color squares, and the king must start somewhere between the two rooks.

Rules

Before the game, a starting position is randomly determined and set up, subject to certain requirements. After setup, the game is played in the same way as standard chess (except that castling can occur from the different possible starting positions for king and rooks). In particular, pieces and pawns have their normal moves, and the objective is to checkmate the opposing king.

Starting position requirements

White pawns are placed on the second rank as in standard chess. All remaining white pieces are placed randomly on the first rank, with the following restrictions:

• the king must be placed somewhere between the rooks
• the bishops must be placed on opposite-color squares

Black's pieces are placed equal-and-opposite to White's pieces. (For example, if the white king is placed on f1, then the black king is placed on f8. Note that the king never starts on the a- or h-files, since this would leave no room for a rook.)

The starting position can be generated before the game by computer program, or chosen by the players by a variety of methods using dice, coin, cards, etc.

Determining a starting position

Main article: Chess960 starting position

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	a	b	c	d	e	f	g	h

Chess960 starting position generated by die rolls:

• 3 (bishop on e1)
• 5 (skip)
• 1 (bishop on b1)
• 4 (queen on f1)
• 6 (skip)
• 2 (knight on c1)
• 1 (knight on a1)

There are many procedures for creating a starting position. A common one is that proposed by Hans L. Bodlaender, which requires only one six-sided die:

1. Roll the die, and place a white bishop on the black square indicated by the die, counting from the left. Thus, 1 indicates the first black square from the left (a1 in algebraic notation), 2 indicates the second black square from the left (c1), 3 indicates the third (e1), and 4 indicates the fourth (g1). Since there are no fifth or sixth positions, re-roll a 5 or 6 until another number shows.
2. Roll the die, and place a white bishop on the white square indicated (1 indicates b1, 2 indicates d1, and so on). Re-roll a 5 or 6.
3. Roll the die, and place the queen on the first empty position indicated (always skipping filled positions). Thus, a 1 places the queen on the first (leftmost) empty position, while a 6 places the queen on the sixth (rightmost) empty position.
4. Roll the die, and place a knight on the empty position indicated. Re-roll a 6.
5. Roll the die, and place a knight on the empty position indicated. Re-roll a 5 or 6.

This leaves three empty squares. Place the king on the middle empty square, and the rooks on the remaining two squares. Place all white and black pawns on their usual squares, and place Black's pieces to exactly mirror White's (so, Black should have on a8 exactly the same type of piece White has on a1, except that bishops would be on opposite colors).

This procedure generates any of the 960 possible initial positions with equal chance. This particular procedure uses an average of 6.7 die rolls. Note that one of these initial positions (rolled by 2-3-3-2-3 or 2-3-3-4-2) is the standard chess position, at which point a standard chess game ensues.

It is also possible to use this procedure to understand why there are exactly 960 possible initial positions. Each bishop can take one of four positions, the queen one of six, and the two knights can assume five or four possible positions, respectively. This leaves three open squares which the king and rooks must occupy according to setup stipulations, without choice. This means there are 4×4×6×5×4 = 1920 possible starting positions if the two knights were different in some way. However, the two knights are indistinguishable during play (if swapped, there would be no difference). So the number of distinguishable possible positions is half of 1920, or 1920/2 = 960. (Half of the 960 are left-right mirror-images of the other half, however Chess960 castling rules preserve left-right asymmetry in play.)

Rules for castling

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An initial position of kings and rooks

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Black has castled h-side (O-O) and White has castled a-side (O-O-O)

Chess960 allows each player to castle once per game, moving both the king and a rook in a single move. However, a few reinterpretations of standard chess rules are needed for castling, because the standard rules presume initial locations of the rook and king that often do not apply in Chess960 games.

After castling, the rook and king's final positions are exactly the same as they would be in standard chess. Thus, after a-side castling (also called sometimes c-castling) the king is on c-file (c1 for White and c8 for Black) and the a-side rook is on d-file (d1 for White and d8 for Black). This castling notated as O-O-O and known as queenside castling in orthodox chess. After h-side castling (also called sometimes g-castling) the king is on g-file and the h-side rook is on f-file. This move notated as O-O and known as kingside castling in orthodox chess. It is recommended that a player state "I am about to castle" before castling, to eliminate potential misunderstanding.

However, castling may only occur under the following conditions. The first two are identical to the standard chess castling rules. The third is an extension of the standard chess rule, which requires only that the squares between the king and castling rook must be vacant.

1. Unmoved: The king and the castling rook must not have moved before in the game, including castling.
2. Unattacked: No square between the king's initial and final squares (including the initial and final squares) may be under attack by any opposing piece.
3. Unimpeded: All the squares between the king's initial and final squares (including the final square), and all of the squares between the rook's initial and final squares (including the final square), must be vacant except for the king and castling rook. An equivalent way of stating this is that the smallest back rank interval containing the king, the castling rook, and their destination squares contains no pieces other than the king and castling rook.

If the initial position happens to be the standard chess initial position, these castling rules have exactly the same effect as the standard chess castling rules. In some starting positions, some squares can stay filled during castling that would have to be vacant in standard chess. For example, after a-side castling (O-O-O), it's possible to have a, b, and/or e still filled, and after h-side castling (O-O), it's possible to have e and/or h filled. In some starting positions, the king or rook (but not both) do not move during castling.

How to castle

When castling on a physical board with a human player, it is recommended that the king be moved outside the playing surface next to his final position, the rook then be moved from its starting to ending position, and then the king be placed on his final square. This is always unambiguous, and is a simple rule to follow.

Eric van Reem suggests other ways to castle:

• If only the rook needs to move (jumping over the king), only the rook needs to be moved.
• If only the king needs to move (jumping over the castling rook), only the king needs to be moved.
• One can pick up both the king and rook (in either order), then place them on their final squares (this is called "transposition" castling).
• One can move the king to its final square and move the rook to its final square as two separate moves in either order (this is called "double-move" castling). Obviously, if the rook is on the square the king will occupy, the player needs to move the rook first, and if the king is on the square the rook will occupy, the player needs to move the king first.

In the meantime there has been an adjustment setting of the WNCA that when performing a castling move it is irrelevant in which sequence involved pieces were touched. All pieces involved in a move may be touched arbitrarily. When castling those pieces are the king and rook, and in capturing moves they are the capturing and the captured piece. Especially with players new to Fischer Random Chess it might make sense also to announce a castling to avoid misunderstandings. When a chess clock will be used, pressing the button could be taken as a sign that a castling move has been completed.

When castling using a computer interface, programs should have separate a-side (O-O-O) and h-side (O-O) castling actions (e.g., as a button or menu item). Ideally, programs should also be able to detect a king or rook move that cannot be anything other than a castling move and consider that a castling move. Recommended gestures are: the king is moving to his at least two steps distant castling target square or else upon the involved rook, to avoid by this a possible confusion with normal king's moves.

When using an electronic board, to castle one should remove the king, remove the castling rook, place the castling rook on its new position, and then place the king on its new position. This will create an unambiguous move for electronic boards, which often only have sensors that can detect the presence or absence of an object on each square (and cannot tell what object is on the square). Ideally, electronic boards should detect a king or rook move that can only be a castling move as well, but users should not count on this.

Gameplay

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In this start position, the a- and b-pawns are unguarded and subject to immediate attack if either side's f- or g-pawns are moved.

The study of openings in Chess960 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. Some starting positions have unprotected pawns that may need to be dealt with quickly.

It has been argued that two games should be played from each starting position, with players alternating as White and Black, since some initial positions may offer White a bigger advantage than in standard chess. For example, in some Chess960 starting positions White can attack an unprotected black pawn after the first move, whereas in standard chess it takes two turns for White to attack and there are no unprotected pawns. (See first-move advantage in chess.)

Recording games and positions

Since the initial position is usually not the orthodox chess initial position, recorded games must also record the initial 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 marked as O-O or O-O-O, just as in standard chess. Note that not all chess programs can handle castling correctly in Chess960 games (except if the initial position is the standard chess initial position). To correctly record a Chess960 game in PGN, an additional "Variant" tag must be used to identify the rules; the rule named "Fischerandom" is accepted by many chess programs as identifying Chess960, though "Chess960" should be accepted as well. Be careful to use "Variant" and not "Variation", which has a different meaning. 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 Chess960. 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.

History

Fischer Random Chess is a variant of Shuffle chess defined by former World Champion Bobby Fischer and introduced formally to the chess public on June 19, 1996, in Buenos Aires, Argentina. Shuffle Chess had been played for quite some time before this, as early as 1842. Fischer's goal was to eliminate what he considered the complete dominance of openings preparation in chess today, and to replace it with creativity and talent. His belief about Russians fixing all international games also provided motivation. 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 each possible opening position would be too difficult to devote to memory (960 "book opening" systems), each player must create every move originally. From the first move, both players have to come up with original strategies and cannot use well-known thinking patterns. Fischer believed that eliminating memorized book moves would level the playing field.

The first Fischer Random Chess tournament was held in Yugoslavia in the spring of 1996, and was won by Grandmaster Péter Lékó.

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 orthodox world chess champion titleholders), but both players were in the top five in the January 2001 world rankings for orthodox 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.

In 2002 at Mainz, an open tournament was held which attracted 131 players. Peter Svidler won the event. Other interesting events happened in 2002. The website ChessVariants.org selected Fischer Random chess as its "Recognized Variant of the Month" for April 2002. Yugoslavian Grandmaster Svetozar Gligorić published in 2002 the book Shall We Play Fischerandom Chess?, popularizing this variant further.

At the 2003 Mainz Chess Classic, Svidler beat Lékó in an eight game match for the World Championship title by a score of 4.5 - 3.5. The Fischer Random Chess (Chess960) open tournament attracted 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 Fischer Random Chess rating list.

Aronian played Svidler for the title at the 2004 Mainz Chess Classic, losing 4.5-3.5. At the same tournament in 2004, Aronian played two Fischer Random Chess 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 Fischer Random Chess. Zoltán Almási won the Fischer Random Chess open tournament in 2004.

In 2005, The Baron played two Fischer Random Chess games against Fischer Random Chess World Champion Peter Svidler; Svidler won 1.5-0.5. The chess program Shredder, developed by Stefan Meyer-Kahlen from Düsseldorf, Germany, played two games against Zoltán Almási from Hungary; Shredder won 2-0. 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 Fischer Random Chess open tournament in 2005. During the Chess Classic 2005 in Mainz, initiated by Mark Vogelgesang and Eric van Reem, the first-ever Fischer Random Chess 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 Fischer Random Chess computer world champion.

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 Fischer Random Chess open tournament, earning him a title match against Aronian in 2007. In 2006 Shredder won the computer championship, making it Fischer Random Chess computer world champion. Three new Fischer Random Chess world championship matches were held, in the women, junior and senior categories. In the women category, Alexandra Kosteniuk became the first Fischer Random Chess Women World Champion by beating Elisabeth Paehtz 5.5 to 2.5. The 2006 Senior Fischer Random Chess World Champion was Vlastimil Hort, and the 2006 Junior Fischer Random Chess World Champion was Pentala Harikrishna.

In 2007 Mainz Chess Classic Aronian successfully defended his title of Fischer Random Chess World Champion over Viswanathan Anand, while Victor Bologan won the Fischer Random Chess open tournament. Rybka won the 2007 computer championship.

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 Kaufmann and FM Mark Duckworth.

Summary table

Year	World Fischer Random Chess Championship	Mainz Open	World Fischer Random Chess Women's Championship	Computer Championship
2001	Péter Lékó (4.5-3.5 vs Michael Adams)	-	-	-
2002	-	Peter Svidler	-	-
2003	Peter Svidler (4.5-3.5 vs Péter Lékó)	Levon Aronian	-	-
2004	Peter Svidler (4.5-3.5 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 (5.5-2.5 vs Elisabeth Pähtz)	Shredder
2007	Levon Aronian (2-2, 1.5-0.5 vs Viswanathan Anand)	Victor Bologan	-	Rybka
2008	-	Hikaru Nakamura	Alexandra Kosteniuk (2.5-1.5 vs Kateryna Lahno)	Rybka
2009	Hikaru Nakamura (3.5-0.5 vs Levon Aronian)	Alexander Grischuk	-	Rybka

Naming

Hans-Walter Schmitt, Frankfurt 2011

This chess variant has held a number of different names. It was initially known as "Fischerandom Chess" after Fischer formalized his variation of Shuffle Chess. Later name forms included "Fischer Random Chess", "FR Chess", and "FRC".

Hans-Walter Schmitt, chairman of the Frankfurt Chess Tigers e.V. and an advocate of this variant, started a brainstorming process for selecting a new name. The new name and its parts had to meet the following requirements of leading grandmasters:

1. it should not contain part of the name of any Grandmaster
2. it should not include negatively biased or "spongy" elements (such as "random" or "freestyle")
3. it should be universally understood

The effort culminated in the name choice Chess960 – derived from the number of different possible starting positions.

R. Scharnagl, another proponent of the variant, advocated the term "FullChess" instead. But today he uses FullChess to refer to variants which consistently embed traditional chess (e.g. Chess960, and some new variants based on the extended 10x8 piece set in Capablanca chess). He currently recommends the name Chess960 in preference to Fischer Random Chess for the variant.

Bobby Fischer never publicly stated his feeling about the name 'Chess960'.

Similar chess variants

Non-random setups

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 colored 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 Chess960 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 Chess960 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 colored squares, if the king is not between the rooks, it should trade places with the nearest rook.

Chess480

Castling in Chess480

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Chess480 castling rule. In Chess 960 the king ends up on either g1 (h-side castling) or c1 (a-side castling). In Chess 480, the king ends up on h1 (h-side castling) or d1 (a-side castling), while the rook ends up on g1 or e1, respectively.

John Kipling Lewis's "Castling in Chess960: An appeal for simplicity" proposes the same rules for the initial position as Chess960, but proposes an alternative set of castling rules. In this variation, the preconditions for castling are the same, 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." Note that these rules are different from the Chess960 rules, since the final position after castling 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"; this variation follows the rules of Chess960 with the exception of the castling rules which Lewis has named "Orthodoxed Castling".

Note also that although the game can start with any of 960 starting positions, half of these are actually mirror positions that theoretically don't change the games' tactics.

Naturally, the right to castle is lost:

• if the king has already moved, or
• with a rook that has already moved.

And castling is prevented temporarily:

• if the square on which the king stands, or the square which it must cross, or the square which it is to occupy, is attacked by one or more of the opponent's pieces.

• if there is any piece between the king and the rook with which castling is to be effected, or on the final square the king is going to occupy.

Note: 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. Another way of defining Chess480 is that the white king must always be located on a dark square. The definition could also be that the white king must always be on a light square. The point is that half the positions are mirror image reversals of the other half. It is really up to the individual to decide how to filter the 480 positions.

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). To quote from the wiki Chess page "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 as attacking weapons (as in many Sicilian variations), 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.

Other related chess variants

There are other chess variants with rules similar to Chess960. These include:

• Chess256 (or random pawns chess): only the pawns are randomized, on the 2nd and 3rd rank. Black's position mirrors White's.
• Corner chess: like Chess960, the placement of the pieces on the 1st and 8th row are randomized, but with the king in the right hand corner. Black's starting position is obtained by rotating white's position 180 degrees around the board's center.
• Double Fischer Random Chess: similar to Chess960, but the opening white and black positions do not mirror each other.
• Transcendental chess: like above, but there is no castling and concept of auction (offering extra moves for the right of picking the side) is added.
• Moab Random Chess: A variant of shuffle chess, using the same initial positions as Transcendental Chess and Double Fischer Random, except that the set-up phase is part of the game. Players take turns placing back-rank pieces on their side or their opponent's. Complex castling rules are replaced with the simple "evacuation" of the king to any empty first-rank square.
• Shuffle chess the parent variant of Chess960. No additional rules on the back rank shuffles, castling only possible when king and rook are on their traditional starting squares.

See also

• Chess variant
• Chess960 numbering scheme

External links

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Descriptions and commentary

• The Birth of Fischer Random Chess
• Chess960.net - Chess960 information: What, where, why and how.
• Audio clip of Bobby Fischer describing his Fischer Random Chess
• Fischer Random Chess Description at ChessVariants.org
• "Leko, the first ever kingpin of Fischer Random Chess"
• Shall We Play Fischerandom Chess? - book by Svetozar Gligorić
• Play Stronger Chess by Examining Chess960 - book by Gene Milener
• Reinhard Scharnagl's (English/German) book Fischer-Random-Schach (FRC/Chess960) ISBN 3-8334-1322-0 (German server)
• CCRL Computer Chess Engines FRC Ratings List

Chess960, servers tools and software

• Lichess - Play Chess960 with a friend or an AI. No registration, no download, no flash. Integrated chat and analyse mode. Opensource website. To castle, drag and drop the king on the destination square unless there is ambiguity with a normal one-square king-move, in which case drop the king on to the rook you want to castle with.
• Chess Hotel - Play Chess960 free in real-time, no registration required, browser-based.
• www.mychess.de - Internet Chess Server - Play Chess960 free in correspondence time, registration required, browser based or with mobile device.
• Free Internet Chess Server - Play Chess960 free, not browser based, with software download interface.
• The Email/Correspondence Chess Club for Chess960
• Arena interface play against an engine or against other people over the Internet
• Fischer random chess generator - online tool to create a random Chess960 position.
• Free web based PGN Player capable of reviewing Chess and Chess960 games. (Broken? Nov 21-10)
• Free web-based player capable of large-scale Chess960 tournaments (scaled for 50,000 players per tournament).
• Scid Vs PC free chess program with the ability to play Chess960 against a computer opponent.
• iTunes Chess960 Calculator
• brettspielnetz.de Chess960 against Java Applet
• ChessManiac.com - Play Chess960 with players from all over the world.
• Meingames.de - Play Chess960 against other people over the Internet.
• Chess.com[1] - Play free online chess, including tournamnets, chess 960, blitz, live chess, and many more.

• Category:Chess variants
• Category:Recurring events established in 2001