13 Ghosts is a microgame for 2-4 players in which each player tries to find the ghost hidden in the opponent's crypt. The game consists of thirteen ghost cards (provided in two sets for use in four-player games), each with a number from 1 to 13 and a special ability.

When playing, you use the card in your hand and you either play it face up to apply its ability or play it face down, thereby attacking your opponent by trying to guess the number of the ghost in their crypt. Succeed, and they are out of the game. As more and more cards are played and abilities are applied, players try to deduce their opponents' ghosts and remove them from the game. The last player to remain wins.