- As in the orthodox game, win by checkmating the king.
- It shouldn't be able to escape the check, not even by moving to the other
- board.
+ Any move played should be legal on the board it is done,
+ and result in a legal situation on the other board. For example
+ 1.Pe4 Pd5 2.Be2!? Sxe4?? 3.Cb5# is checkmate because
+ 3...Kd7 is not valid on board 1.