Castling in Chess960: an appeal for simplicity

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The intention of this article is to promote the idea that the castling rules as originally presented by Bobby Fischer for Chess960 are flawed from a game design standpoint and that changing these rules would benefit the advancement and acceptance of Chess960 by both the Standard Chess and non-chess playing communities.

9/11/2005

That's basically it. You can learn the rules in two minutes. It's a great game, and can become the standard for chess.

Bobby Fischer

In 2003 David A. Wheeler contacted many active in Fischer Random Chess to determine the exact castling rules, including Eric van Reem, Hans-Walter Schmitt, and R. Scharnagl. All agreed that there must be vacant squares between the King and his destination except for the participating Rook, clarifying the castling rules for Chess960.

The intention of this article is to promote the idea that the castling rules as originally presented by Bobby Fischer for Chess960 are flawed from a game design standpoint and that changing these rules would benefit the advancement and acceptance of Chess960 by both the Standard Chess and non-chess playing communities.

First let's review castling rules for Fischer Random and Standard Chess.

Fischer Random castling rules (quoted from http://www.chessvariants.org/diffsetup.dir/fischerh.html)

Of necessity, in Fischer Random Chess the castling rule is somewhat modified and broadened to allow for the possibility of each player castling either on or into his or her left side or on or into his or her right side of the board from all of these 960 starting positions. However, after "a"-side castling, the King and Rook find themselves on the usual squares: King on c1 (c8) and Rook on d1 (d8), after "h"-side castling : King on g1 (g8) , Rook on f1 (f8). Sometimes castling looks odd in Fischer Random Chess: e.g when your King is on e1 and a Rook is on f1, you only have to move your King to g1 ("King-move-only" castling).

A much longer explanation can be found at http://home.att.ne.jp/moon/fischer/list/p_20/20_0.htm, from the original Fischer Random text.

FIDE rules for castling (quoted from http://www.fide.com/official/handbook.asp?level=EE101)

Castling: This is a move of the King and either Rook of the same colour on the same rank, counting as a single move of the King and executed as follows: the King is transferred from its original square two squares towards the Rook, then that Rook is transferred to the square the King has just crossed.

Please note that for brevity I have excluded from both the conditions under which castling is not allowed. I will include these for the offered variation at the end of this article.

I think it's important to review a history of castling to understand part of the impetus for this change. Before the 1500s, in order to speed up the game, the 'King's Leap' allowed the King to move two spaces as his first move (jumping one square). Castling become a single move of a rather common two move opening where the Rook was moved next to the King and the King would use his King's Leap to move on the other side of the Rook on the following turn.

There are two points to be made here. The first is the King's ability to 'King's Leap' two spaces as his first move was changed to castling as a single move. This is a balancing of power from a game design point of view, because the King can no longer move forward or diagonally two squares on the 'King's Leap', but must instead interact with a Rook in order to gain the advantage of moving two squares as his first move. The second point is that the Rook always ends up in the square leaped over by the King. (further research available at http://cunnan.sca.org.au/wiki/Chess)

In examining Bobby Fischer's rules for Chess960's castling we see that it totally ignores the origins of castling in favour of appealing to chess players who are already familiar with the castling positions that result from Standard Chess. Unfortunately the system is confusing to newer players who aren't as familiar with Standard Chess. The final resting squares of the King and Rook feel arbitrary to new player who may not have played enough Standard Chess to intuitively remember them.

It seems that simplification of the castling rules for Chess960 could help promote the game for beginners, streamline the rules and reconnect the game with it's historical roots. To that end I suggest the following castling rules for Chess960:

Castling: This is a move of the King and either Rook of the same colour on the same rank, counting as a single move of the King and executed as follows: 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 can not move two spaces over the Rook, then the King and Rook exchange squares.

  1. The right for castling has been lost:
    1. if the King has already moved, or
    2. with a Rook that has already moved
  2. Castling is prevented temporarily
    1. 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.
    2. if there is any piece between the King and the Rook with which castling is to be effected.

This rule is much cleaner than the current set of rules and is the most obvious to new players who are introduced to Chess960 as beginning Standard Chess players. As an exercise for the reader, I suggest finding a new Standard Chess player, explaining the rules of Chess960 to them without revealing how castling works, and then ask them to guess how castling would work in the variant you have just shown them.

Examples

White is the current system. Black is the proposed system.

King starting on d-file (The odd case of the King starting in the Queen's position)

Before  After

King starting on b-file (The fastest King example)

Before  After

King on c-file, rook on e

Before  After

Comments

AuthorComment
Archr
9/29/2005 1:07 AM
The previous author makes a great case. It is virtually beyond contradiction that the proposed change is in greater accord with the historical development as the preceding author presents that history. And certainly, the proposed change is far easier to explain to beginning 960 players (particularly those who have not played standard chess first).

Fischer seemed to desire FRC to replace standard chess. And yet, FRC castling makes no sense without knowing standard chess. To have FRC castling rules so dependent for their explanation on one particular position of the almost 1000 possible starting positions strikes me as inconsistent with that goal--and backwards.

However, it is apparent that the chess community will not easily change. 960 will not change--not now.

Despite my enjoyment of 960, I can hope that a new FRC variant with improved, simpler, and more natural castling rules can achieve equality in the minds of 960 players.

The corrected variant will be the one that I teach my children.

(But when I play Chess960, I will always enjoy castling h-side when the king starts on the b-file!)
nasmichael
12/24/2005 5:51 PM
I show young people how to play the standard game--if I were to spring the rules of Chess 960 on them, they would blow a fuse. But, as they recognize patterns so quickly, they would become acclimated to the possibilities. If I went from the standard to chess480, the castling rule "king moves 2 squares to the left or right, and rook comes to guard him" works in either case. Maybe both 480 and 960 can coexist. After all, the castling rules came along well after the game was established, and the codification of castling was solidified (with some resistance from the Italian Masters up into the late 1800s) only at the end of the 19th century. Even at that time, masters could still choose which side went first in their match games (see Saint-Amant v. Staunton, London, April 28th, 1843, 1st match, colors reversed--ref. James Gelo's Chess World Championships, 1834--1998, 2nd edition). So there is still in the playing community some wiggling room, as each game is an agreement between players.

Mekk
7/25/2006 1:45 PM
I like the current Chess 960 castling rules (after the castling pieces stay as in normal chess). In my opinion they are both simple, and lead to natural position of the pieces.
woodpusher
2/22/2007 12:11 AM
I posted some contrary arguments on this in the Forum under Chess Chat: Castling Rule Controversary. Still like my position there after reading this. (Discussion is good.)
woodpusher
2/22/2007 12:16 AM
Since I don't know how long these comments will be available on the Chess Chat forum, I'm posting them here as well.

The castling rule for Standard, 960, and Double960 (actaully 960x960) chess is the best option.

The reason can be found in contemplating that the rules of chess have evolved over a thousand years guided by a purpose: to make the game more enjoyable for casual players and masters alike. It is easy to see how the introduction of the initial two-square option for pawns, increased power of the queen, and time limits served this purpose. They both sped up the play to a practical time frame and enhanced the strategic and tactical richness.

Castling, by getting the king quickly out of the dangerous and strategically important center of the board, eliminated cumbersome, time consuming maneuvers, made an early connection of the two rooks, and allowed players to focus on the strategy of battle. The strategic and tactical themes were enriched due to the delay in getting at the king’s position.

The Chess480 castling rule trades away the principles of early king safety and focus on battle strategy (although these are often preserved in practice) for simplicity or consistency in applying the rule.

It may be argued that the considerations I’ve raised suggest that the castling rule should be changed to always move the king to the knight’s file and the rook to the bishop’s file, whether on the queen side or king side. Perhaps so, if Chess960 had been the original game. However, the original castling rule was developed from an earlier rule that allowed the king to move two squares (if in check, if in check the first time, or something like that?) in an early effort to make the game more interesting.

Today, we have a rich tradition and treasure of chess strategy around the Standard Chess position. This is worth preserving, enjoying, exploring, and participating in. The traditional castling rule is part of all this, and it is functional in its own right. Study of this treasure will pay dividends in playing the randomizing variants of chess as well.

In particular, Chess960 and, to a lesser extent, Chess960x960 (Double Fischer Random) are valuable additions to the game, while preserving traditional strategic principles of play (control over the center, king safety, and such).

Standard Chess at the master level has come to require enormous knowledge of opening variations, removing the game from the scope of those who do not devote their lives to chess, and rendering that level of play less interesting to all but other masters.

As is generally recognized and applauded, the new random variants, by getting out of “the tactical book,” refocus the game on developing strategic principles and improvising tactics accessible to the understanding of the general chess community.

Standard Chess will always be the special position of Chess960: the standard, if you will. It is the position to study for developing skills. Preserving its castling rules is part of that process and connective reference.

woodpusher
2/27/2007 10:01 PM
Relevant to the point of explaining castling, please see my post in the Chess960 forum: Explaining Castling in Chess960. I am interested in challenges to my position. Thanks.