In Cult of the Lamb, the player is guided by the mentor Ratau about several basics to managing a cult. Strangely enough, he also introduced us to Knucklebones, a fan favourite minigame. Any time between crusades, the player can visit Ratau to wager coins in this minigame that is both a mix of strategy and luck. Further into the game, the player can unlock more characters to play against, such as Flinky, Klunko and Bop and Shrumy, in that order of difficulty.
Correction
Um actually … You cannot play against Ratau at every point in the game. There is a series of event with the Fox which culminates in sacrificing Ratau, after which he is no longer available for Knucklebones. :::