Twins Chess

Standard array on an 8 by 8 board. Pairs of Rooks, Bishops and Knights are Twins. Twins both move during a turn. If one can not move, the other may not move. If either is captured, both are removed from the board. Non-twin pieces (Pawns, Queens and the King) move singly.

Twins that are mutually guarding each other may make recaptures. For example, if White has Knights at a1 and c2 and a Pawn on d2, and Black moves Bd3xc2 and Bc3xd2, both Knights, both Bishops and the Pawn are all removed from the board. If however, from the same board situation the Black Bishops move Bd3xc2 and Bc3xa1 capturing both Knights indiviually, the Knights are removed from the board but both Bishops survive.

- - - - - - - -  8          - - - - - - - -  8
- - - - - - - -  7          - - - - - - - -  7
- - - - - - - -  6          - - - - - - - -  6
- - - - - - - -  5          - - - - - - - -  5
- - - - - - - -  4   --->   - - - - - - - -  4
- - b b - - - -  3          - - - - - - - -  3
- - N P - - - -  2          - - - - - - - -  2
N - - - - - - -  1          - - - - - - - -  1
a b c d e f g h             a b c d e f g h   

Starting Position                 after         
                            Bd3xc2 and Bc3xd2 
             


- - - - - - - -  8          - - - - - - - -  8
- - - - - - - -  7          - - - - - - - -  7
- - - - - - - -  6          - - - - - - - -  6
- - - - - - - -  5          - - - - - - - -  5
- - - - - - - -  4   --->   - - - - - - - -  4
- - b b - - - -  3          - - - - - - - -  3
- - N P - - - -  2          - - b P - - - -  2
N - - - - - - -  1          b - - - - - - -  1
a b c d e f g h             a b c d e f g h   

Starting Position                 after         
                            Bd3xc2 and Bc3xa1 

Pawn promotions may be handled one of two ways, players deciding before starting, or leaving both choices open during play:

1. Pawns promote to single piece that becomes a Sibling with other friendly pieces of same rank. All siblings move or none may and if one is taken, all are removed. For example, the player promotes a pawn to a second queen -- the queens are now Twins. Or the player promotes a pawn to a third knight -- the three knights are now Triplets. If there are no pieces on the board matching the chosen rank, the piece is a single normal non-twinned piece.
2. Pawns promote to Twin pieces on the promotion square. These Twins are not siblings to existing friendly pieces. When they move again, they must move to separate squares and may never share a square again. If they are captured before they move, both are removed. For example, a player with Twin Knights on the board promotes a pawn on e8 to another pair of Twin Knights. The player now has two unrelated sets of Twin Knights on the board. The player's next move could be: e8 to d6 and f6.

Minor Variations

1. Queen and King are twins, effectively making both pieces royal.
2. Game starts with twin Queens on d1 and d8. Once they move, they may never share the same square again. They may be captured together before they make their first moves.
3. Twin Queens only. As (2) but other array pieces and promoted pieces are not twins.
4. Twins *may* share the same square at any time.

Major rules variations

5. Separated at Birth -- Move alone, die together. a) Player may move one or both Twins, but if one is captured, both are removed. b) As (a) but only one move per turn under all circumstances.
6. Identical Twins -- Move together, live alone. Twins move together as in original game but captures of one sibling do not affect the others.
7. Fraternal Twins -- Non identical pieces are twins, for example, adjacent Bishops and Knights in the starting array are Twins. Played as the original game or using variation (5) or (6).