Slot Machine Chess

A slot machine spins at the start of your turn and pick which pieces may move.

At the start of your turn three rollers spin, each landing on one of the piece TYPES you still have on the board; every roller is one move credit for that type. The same piece may spend several credits in one turn. Your turn ends by itself the moment no credited piece has a legal move, a completely unplayable spin simply passes after a beat. Castling costs only a king credit (the rook comes along free).