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 pieces is randomized along the players’ home ranks. 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 on a square between the rooks.
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).
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.)
Chess960 allows each player to castle once per game, moving both the king and a rook in a single move.
After castling, the rook and king’s final positions are exactly the same as they would be in standard chess.
Castling may only occur under the following conditions.
- Unmoved: The king and the castling rook must not have moved before in the game, including castling.
- 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.
- 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.