In Gates of Delirium, players have a hand of split action cards: one side sane, and the other insane. Every round, one player decides whether the round is sane or insane, and all players must play that side of their cards. During sane rounds, players search for maps and lost pages to a secret tome, while assigning investigators to help them in their cause. During insane rounds, players collect ancient runes and work to build gates to release the monstrosities that their sane selves have been trying so hard to understand and prevent. Earn the most victory points by the time the last monstrosity is released to win Gates of Delirium.