The game is based on XII, a Belgian graphic novel about an amnesiac who seeks to discover his past. This game is illustrated by drawings from the graphic novel. In this card game, one player takes over the role of XIII every turn of the game. Other players receive secret roles based on the major characters of the book. Those secret roles can be allies or enemies of XIII. The player playing XIII will reveal a mission with a number. At their turn, players will play action cards with a positive or negative value. The player who reach the mission number wins the mission and XIII draws the next mission card. A round ends when the card pile empties. Each player then scores as many points as he succeeded missions. If XIII has an ally, they both share their points and the next player around the player takes on the role of XIII. The player with the most points at the end of the last round wins the game.