Chess960 Rules at chessmail

Chess960, also known as Fischer Random Chess, is a chess variant where the starting position of the pieces on the back rank is randomised. This eliminates the advantage of memorised openings — players must rely on their own thinking from the very first move.

The standard chess rules at chessmail apply, with the following differences.

The Starting Position

In Chess960, the pieces on the back rank (rank 1 for White, rank 8 for Black) are arranged randomly. Three rules must be followed:

  • The two Bishops must be placed on squares of different colours.
  • The King must be placed between the two Rooks.
  • Black's pieces are placed in a mirror image of White's.

These rules produce exactly 960 possible starting positions — hence the name. The Pawns are placed on the second rank as usual.

The standard chess starting position is one of the 960 positions (No. 518).

Castling in Chess960

Castling in Chess960 works in principle the same as in standard chess — but since the King and Rooks may start on different squares, there are some special considerations.

The End Result Is Always the Same

Regardless of the starting position, the King and Rook always end up on the same squares as in standard chess after castling:

  • Kingside castling (0-0): The King ends up on g1 (or g8), the Rook on f1 (or f8).
  • Queenside castling (0-0-0): The King ends up on c1 (or c8), the Rook on d1 (or d8).

Conditions for Castling

As in standard chess, the following conditions apply:

  • Neither the King nor the involved Rook may have moved previously.
  • The King must not be in check.
  • No square that the King crosses or lands on may be attacked by an opponent's piece.
  • All squares between the starting and ending positions of both the King and the Rook must be empty (except for the King and Rook themselves).

Special Cases

Since the King and Rook can start on unusual squares in Chess960, some special situations can occur:

  • The King may remain on its starting square during castling (if it is already on the destination square).
  • The Rook may remain on its starting square during castling (if it is already on the destination square).
  • The King and Rook may swap places during castling.

At chessmail, castling is performed by moving the King onto the Rook you wish to castle with.

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