The idea is a very simple one: each army has problems in specific board areas, white
pieces in black squares and vice versa! That reminds me of the eternal struggle between
Good and Evil.
Hell and Heaven
All FIDE rules apply, except:
White pieces at black squares, and black pieces at white squares cannot capture.
The black bishop (the good demon) at c8 belongs to White and the white bishop (the bad
angel) at c1 belongs to Black. This means that each bishop is moved by the other player.
However their color remain unchanged, so Black (White) cannot capture the good demon (bad
angel). They can be used to block the opponent and still be captured by their respective
owners.
note: If you think the game turn out to be too passive, you can always increase the
armies power. A possibility is to change the Rooks by Rooks+Knight pieces.
