Weird concept app. Essentially, first you tap the screen the same number of times as the value of the card (ace is 1 and jack, queen , king are 11, 12, 13 respectively), then hold down for more than 1 second. Then you tap in the suit of the card in the CHaSeD order. (Clubs Heart Spades Diamonds) with 1=Clubs and so on. Then click Scratch Cat to reveal the card that you encoded. Let me know in the comments if that makes sense.
Original idea and code be me.
