Basic Rules
As a main stream chess variant, B.O. Chess gets most of its rules from standard chess. All rules concerning draws, perpetual check, etc. apply. The game ends in the same way standard chess does: by check-mating the opposing king.
Piece Movement
- Pawns may move up to 4 squares on their first move. After the first move a pawn may always move forward one or two squares except when moving to the last rank. A pawn may only move to the last rank by moving forward one square. A pawn reaching the last rank promotes to any piece except king or pawn. Thus it takes at least five moves for a pawn to promote. Except for en passent, pawns capture exactly as they do in standard chess. En Passent capture is allowed immediately following a turn in which a pawn has moved past the square attacked by an opposing pawn on an adjacent file. The capturing pawn moves in the usual way to the square it attacks. Note that En Passent capture is not only a possibility after a pawn's first move, but also after any pawn move of 2 squares.
- The standard chess pieces: Rook (R,*R), Bishop (B,*B*), Queen (Q,*Q), and King (K,*K*) move and capture exactly as in standard chess. The ranges of the Rook, Bishop, and Queen extend to the entire board.
- Castling is permitted under exactly the same rules as ordinary chess, except that the King moves 3 squares instead of 2. The squares between the King and the rook to be moved must all be empty and not under attack, and the King the rook may not have moved.
- The Guard (G,*G*) takes the place of the ordinary knight in B.O. Chess. The guard moves and captures at any adjacent diagonal square, and also leaps and captures in a 3x1 "L"-shape: 3 squares forward, backward or sideways followed by one square in a perpendicular direction.
- The Matriarch (M, *M*) (or Outer Queen) moves as a standard queen from the outer zone. A Matriarch on a square in the mid-zone moves as a standard queen, but no more than 6 squares in any direction. A Matriarch on a square in the central zone moves as a standard queen, but no more than than 3 squares in any direction.
- The Jumper (J, *J*) is an outer piece which can always move and capture like a king, one square in any direction. In addition, a jumper in the outer zone may leap and capture 3 squares forward, backward, sideways, or diagonally. In the same way, a jumper in the mid-zone may move one square in any direction, or leap and capture 2 squares forward, backward, sideways, or diagonally. Jumpers in the central zone may move and caputer only one square in any direction.
- From the central zone the Outer Knight (N, *N*) leaps and captures exactly as an ordinary knight. From the mid-zone an Outer Knight leaps "3x1" or "2x2": i.e. 3 squares forward or backward and 1 square sideways, 3 squares sideways and 1 squares forward or backward, or 2 squares forward or backward and 2 squares sideways. From the outer zone the Outer Knight leaps "4x1" or "3x2".
Initial Position and Notation
- Notation is much like algebraic notation for ordinary chess. Ranks are numbered 1-12. Files have letters a-l. The additional corner squares are numbered C1,C2,C3,C4, starting on White's King side and going around counter-clockwise.
- A diagram of the initial position of the pieces is given below. Knights start in the corner squares C1,C2,C3, The other white pieces are arranged in rank 1 in the order: J R M G B K Q B G M R J. Twelve white pawns start out in the squares of rank 2. Black's initial position is a mirror image of White's.
- Diagram of the board with initial position and zones:
