Introducing: 69 Chess
What about it?
Both of player will lose the same piece that was captured by anyone but here's the catch. The one who captured the piece will be the one to choose which among their own piece will be sacrifice(must be the same type of piece got captured). Eg.: If you captured the oppositing rook, You can choose among two of your rooks gonna sacrifice.
Two conditions of winning: 1)Checkmate and 2)No more sacrifice[Capturing a rook when you dont have a rook will result on your lose.]