Checking how original this card game mechanic is.

I'm currently designing a couple of easy to mid complexity games for a contest and one of them is based upon an idea I had around the design of the card itself. The card would have two holes (both on the same short side or in opposite corners, like poker playing cards) that would let the players stack the cards in different ways to see through them.

I know that there's a pokemon card game out there with transparent cards, but maybe the biggest reference when it comes to seeing through is Gloom. Since my approach wasn't quite the same as the one used in Gloom, I came to ask if you knew any other games that made use of any kind of transparency or hole in the cards themselves.

Much appreciated