Chess960

Chess960

One of 960 possible starting setups. Black's setup always mirrors White's.
Years active	Since June 19, 1996
Genre(s)	Board game Chess variant
Players	2
Setup time	~1 min.; an additional min. to determine starting position
Playing time	Casual games: usu. 10–60 mins. Tournament games: from 10 mins. (fast chess) to 6+ hrs.
Random chance	None
Skill(s) required	Strategy, tactics
Synonym(s)	Fischer Random Chess (FRC) Fischerandom New Chess

Chess960 (also known as Fischer Random Chess or Fischerandom) is a variant of chess invented and advocated by former World Chess Champion Bobby Fischer, publicly announced on June 19, 1996, in Buenos Aires, Argentina. It employs the same board and pieces as standard chess; however, the starting position of the pieces on the players' home ranks is randomized. The random setup renders the prospect of obtaining an advantage through the memorization of opening lines impracticable, compelling players to rely on their talent and creativity.

Randomizing the main pieces had long been known as Shuffle Chess; however, Chess960 introduces restrictions on the randomization, "preserving the dynamic nature of the game by retaining bishops of opposite colours for each player and the right to castle for both sides". The result is 960 unique possible starting positions.

In 2008 FIDE added Chess960 to an appendix of the rules of chess.

Before the game, a starting position is randomly determined and set up, subject to certain requirements. After setup, the game is played the same as standard chess in all respects, with the single exception of castling from the different possible starting positions for king and rooks.

White pawns are placed on the second rank as in standard chess. All remaining white pieces are placed randomly on the first rank, with two restrictions:

Black's pieces are placed equal-and-opposite to White's pieces. For example, if the white king is randomly determined to start on f1, then the black king is placed on f8. (The king never starts on the a - or h -file, since this would leave no space for a rook.)

Each bishop can take one of four positions; for each position of two bishops, the queen can be placed on six different squares; and then the two knights can assume five or four possible positions, respectively. This leaves three open squares which the king and rooks must occupy per setup stipulations, without choice. This means there are 4×4×6×5×4 = 1920 possible starting positions if the two knights were different in some way. The two knights are indistinguishable during play (if swapped, there would be no difference), however, so the number of distinguishable possible positions is half of 1920, or 1920÷2 = 960. (Half of the 960 positions are left–right mirror images of the other half; however, Chess960 castling rules preserve left–right asymmetry in play.)