 Castling and "en passant" captures are not permitted.Announcing a check is not obligatory, and "snaffling" (winning the game immediately by capturing the opponent's king after he either moved into or failed to move out of check) is allowed – and has on more than one occasion decided a world championship game.Orthodox chess generally assigns the pieces relative values of 9 points for a queen, 5 for a rook, 3 for a bishop or knight, and 1 for a pawn; although no attempt has been made to assign specific values for circular chess, it is certain that the same values do not hold.