Rules for Castling in Chess960

Rules for Castling in Chess960 (Fischer Random Chess)

Due to the different starting positions, castling in Fischer Random Chess (FRC) might look quite complicated to a new player. The rules are actually very easy to learn because they have not changed. So if you are familiar with the castling rules for standard chess, you will be fine.

As in standard chess, Fischer Random chess960 allows each player to castle once per game. After castling, the king and rook's final positions are exactly the same as they would be in standard chess. Thus, after castling a-side (known as 0-0-0 or Queen-side castling in standard chess), the King lands on the c-file (c1 for White and c8 for Black) and the Rook is on the d-file (d1 for White; d8 for Black). After castling h-side (known as 0-0 or King-side castling), the King lands on the g-file (g1/g8) and the Rook on the f-file (f1/f8).

The rules for castling in FRC are the same as those in standard chess:

1. Unmoved: The king and the castling rook must not have moved before in the game, including castling.
2. Unattacked: All of the squares between the king's initial and final squares (including the initial and final squares) must not be under attack by any opposing piece.
3. Vacant: 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.

These rules have the following consequences:

• 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.
• All the squares between the king and castling rook must be vacant.
• Castling cannot capture any pieces.
• The king and castling rook cannot "jump" over any pieces other than each other.
• A player may castle at most once in a game.
• If a player moves his king or both of his initial rooks without castling, he has lost the ability to castle for the rest of the game. If only one rook has been moved, the king may not castle using that rook, and thus may not castle to that side of the board.
• In some FRC positions, it is possible to castle if the a, b, or h squares are occupied. This is because the king does not land on these squares after castling, nor does the king travel through them.
• The king may not be in check before or after castling.
• The king cannot move through check.

http://www.youtube.com/watch?v=wuUBLw9eabk&feature=player_embedded

A visual example about how to castle.

An interesting puzzle to solve (and understand Chess 960 castling rules):

I've solved it! Nice, the winning move is to castle!

OK, Thanks. Its to necessary to know this castling rules as well as situation to clear it.

From reading John Nunn's book "Solving in Style", in traditional chess1-based puzzles it is assumed that castling is still legal if the king and rook are still on their starting squares.

But in a chess960 puzzle it often becomes necessary to explicitly state whether castling is still legal.
The so-called Shredder-FEN notation is probably best for this.

Suppose the chess960 start position is NRBK-QBRN.
If all four castlings are still legal, Shredder-FEN notates that as BGbg (or BbGg, any sequence is fine); because those are the start columns of all rooks that are still able to participate in castling.

Chess1 FEN is limited to KQkq, to denote the king and queen wings/sides of the board. Obviously KQkq works only for chess1, while Shredder-FEN works for chess1 and all of chess960 equally well.

Fritz_9 onward wisely accepts Shredder-FEN for both chess1 and chess960.

THAT CASTLING WAS ILEGAL

 Which one? can you explain why you think it was illegal?

I may be misreading it, but rule "K" under castling in Fischer's rules states that you cannot castle into check.  Does that make this move illegal or am I mistaken in my interpretation. 

I didn't think that you  could castle in this position .

I[ve also never seen this starting position  , the king must be  in this  spot  since the beginning or castling would be illigal . So I still think that  this position is not possible . I agree with vic 9 .

I've tried this move on a chess.com 960 game and it won't accept it.

It is Chess960, my good sir.