The basic structure of the game is this: the deck has 55 cards, with eight symbols on each card, culled from a bank of 57 symbols in total. If you choose any two cards at random, one symbol always matches. The game provides several different ways to play, but they all hinge on the speed with which you spot the match—the two blocks of cheese, the ink spots, the dolphins, the snowmen and so on.
But how—how!?—is it possible that every single card matches another card in just one way?
It’s not magic. It’s math.