Editing Chess960 (section)

==Similar variants==
There are several 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."<ref>Pritchard (2000), p. 17.</ref>

{| class="wikitable"
|+ Summary
|-
! Variant !! Under condition<br/>(and all of the above) !! Positions<br/>with symmetry<br/>a1 to h1 = a8 to h8 !! Positions<br/>with symmetry<br/>a=h, b=g, c=f, d=e<br/>(king=queen)
|-
| '''Shuffle chess''' || Random || 5040 || 48
|-
| '''Chess2880''' || Bishops opposite color || 2880 || 48
|-
| '''Chess960''' || King between rooks || {{0|0}}960 || 16
|}

'''Remarks'''

Any variant with N starting positions can exist with mirroring (or rotating) white and black otherwise it means another (double) variant with N<sup>2</sup> starting positions. In any variant the castling is not possible in any case or is possible only when king and rook are on their traditional starting squares, or as follows:

After castling with the nearest rook to the column:

* "h", the king will be in column "g" and the rook will be in column "f".
* "a", the king will be in column "c" and the rook will be in column "d".

The double chess2880 without castling is known as [[Transcendental chess]] (or TC).

'''Chess18''' is the subset of Chess960 in which the kings and rooks are fixed, so that castling is always orthodox, preserving more of the feel of ordinary chess. This allows some opening knowledge to still have practical relevance – one could practically learn a few short lines for each of the eighteen starting positions – though it does not reach the extent of orthodox chess, in which one has to memorize many long computer lines. Moreover, this excludes all starting positions where White has a large advantage, and makes early blunders less common by making it impossible for a bishop to attack an undefended pawn after White's first move.<ref>{{cite magazine |last=Kaufman |first=Larry |date=August 2023 |title=Chess18 |url=https://pubs.royle.com/publication/?m=40761&i=797200&p=26&ver=html5 |magazine=Chess Life |location= |publisher=US Chess Federation |pages=24–26 |access-date=11 January 2024}}</ref><ref>Weeks, Mark. [http://chessforallages.blogspot.com/2022/09/chess324-is-thing.html "Chess324 Is a Thing"], 2022-09-05.</ref><ref>Kaufman, Larry. [https://talkchess.com/forum3/viewtopic.php?f=2&t=80482&sid=6aafd4012be37101dcfe60786a173cb5 "Chess324"], 2022-08-12.</ref><ref>[https://www.sp-cc.de/anti-draw-openings.htm Stefan Pohl, Anti Draw Openings]</ref> However, due to having fewer starting positions and the requirement that the king and rooks must start on traditional starting squares, Chess18 has much less positional diversity than is offered by Chess960. Additionally, while memorizing openings is more difficult in Chess18 than in traditional chess, opening preparation has the potential to be a much more significant aspect of the game than in Chess960, especially for grandmasters and top players. Chess18 positions are more likely than Chess960 positions to resemble structures found in traditional chess due to the limited starting positions in Chess18 in comparison to the diversity of starting positions found in Chess960.
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 |Starting position, game 4 ("Both players have bad positions." —{{hair space}}[[Helmut Pfleger]]<ref>Gligorić (2002), p. 115.</ref>)
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As discussed above in 'Castling rules', '''Chess870''' and '''Chess90''' are the partitioning subsets of Chess960 in which a player, respectively, never needs or may need to give up castling rights on one side to castle on the other side.<ref name="chess.stackexchange.com"/><ref name="Sesse 1" /><ref name="Sesse 2" /><ref name="ReferenceA"/>

'''Chess480'''<!-- A page will be created for this variation when it is more widely accepted.
We don't need to note 'future work' in the printed version of the article. -->

In "Castling in Chess960: An appeal for simplicity", John Kipling Lewis proposes alternative castling rules which Lewis has named "Orthodoxed Castling".<ref>Lewis, John K. [http://www.chessvariants.org/diffsetup.dir/castling_960.html "Castling in Chess960: An appeal for simplicity"], 2005-09-18.</ref>

The preconditions for castling are the same as in Chess960, but when castling,
<blockquote>... 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.</blockquote>

{| align="right" 
|-valign="top" 
|+ Examples of Chess480 castling
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 |An initial position of kings and rooks
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 |White has castled h-side (0-0) and Black has castled a-side (0-0-0).
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Unlike Chess960, 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"<ref>O'Shaughnessy, David. [http://chess960.net/castling-in-chess480 "Castling in Chess480: An appeal for sanity"] {{webarchive |url=https://web.archive.org/web/20120321024225/http://chess960.net/castling-in-chess480 |date=March 21, 2012 }}, 2008-11-22.</ref> 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). 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 [[pawn storm]]s, 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.