I should probably have posted this here, rather than on the "Chess variants (8x8)" board.

I'd like to see Compromise Chess added. It seems to me to be a close cousin (or maybe just an older aunt or uncle) of Ambiguous Chess.

Rules summary: player to move proffers 2 candidate moves (except in cases of forced or "only" moves--which are directly made); the other player decides which of the 2 candidate moves is actually played. (That's why it's a compromise: both players help determine what's actually played.)

Where things get really interesting: captures, checks, and responses to them.