Clack! is a collectible trading card game played by the nerdier inhabitants of Barrow's Maw.¹⁾

The exact rules of the game are unknown— different players may even play by different rules!— but the general mechanics revolve around Clack! cards and marking damage upon them.

Clack! cards are rectangular wooden slats graven with the image of monsters. These monsters are played and made to fight, until one players declares that they have won. Arguments may then ensue, especially if bets have been made.

Though official Clack! cards are manufactured solely by the Clack Consortium, a number of unofficial versions have sprung up, including Thwack! cards which depict individual and well-known figures of the Maw rather than generic monsters.

Despite what Clack! players would have you believe, Clack! cards are in fact utterly worthless.