Cthulhu Fluxx

From BoardGameGeek.com:

Explore the dark and horrifying mysteries of the unknown as you battle insanity and fiendish cults in Cthulhu Fluxx! Follow the wild-eyed Poet, the obsessed Artist, and the expeditions of the Professor as they investigate Eldritch Secrets no mortal was meant to discover. Someone has stolen the Necronomicon from the library at Miskatonic Univeristy, and a Farm in the hills is undergoing a horrifying Metamorphosis. Meanwhile, unspeakable abominations stir in Penguin-riddled Tombs beneath the ice. Are you Inevitably Doomed to a lifetime of Nightmares in the Sanitarium, or are you, in fact, a Secret Cultist, worshiping the Minions of Darkness?

Like the other games in the Fluxx family, in Cthulhu Fluxx players will modify the rules of the game by playing cards, changing numerous aspects of game play: how many cards to draw or play, how many cards you can hold in hand or keep on the table in front of you, and of course how to win the game. Players collect Keeper cards to satisfy the victory requirements but watch out for Cthulhu and other fiendish Creepers that will prevent you from winning – even if you otherwise have the winning combination!