Berolina Chess with Different Armies
Of course, you can take any random chess variant and play it with the standard different armies; but Berolina Chess is an especially interesting choice because it raises the question of how much do the values of the pieces depend on the way the Pawns move?Berolina Pawns move diagonally and capture straight forward, and so for example a Rook cannot sit behind a Pawn and push it in to Queen, and a Bishop cannot be defended by a Pawn that the Bishop in turn defends.
I have looked at this game with the Fabulous FIDEs, the Colorbound Clobberers, and the Remarkable Rookies. I find that it works, and it presents interesting challenges.