Piledriver Chess
 
You will need: 
A chess set
Two cards for each player for each piece in the game. So each player
will have 2 cards that say Pawn, two cards that say Rook, two cards
that say King, etc.
 
Setup is the same as in normal chess. However, at the beginning of the
game, each player lays one of his cards face down in front of him.
 
Play is as normal chess, except that at the beginning of your turn,
flip face up the card that was placed facedown. This is the type of
piece you must move this turn. After you flip up the card, place a new
card underneath the old one face down. Then make your move. At the end
of the turn, return the face up card to your hand, and the turn passes
to the other player. 
 
Exception: If your King is in check, you may move any of your pieces,
despite what card you put down.
 
Checkmate: The game ends in checkmate as normal, even if the next card you play would not capture the King.
 
Original credit for the mechanic goes to John Cooper, who made it for
another game but decided not to use it. So I took it and made it a
chess variant.