La Vallée des Rois: L'Éveil de Nyarlathotep is a 32-card expansion that transforms La Vallée des Rois into something of a different game as now one of the adventurers leads a cult and plans to use the treasures found in the tombs to carry out their evil plans, while the opponent tries to stop him with the help of a handful of scholars and courageous investigators. Each player has a deck of ten specific cards that includes allies, traps and equipment, from which they draw one card per turn. The three papyrus received by the cultist player early in the game does not come from the usual papyrus, but six "Cthulhu Mythos" papyrus that cite terrible deities and avatars such as Nyarlathotep Yig or that cast spells causing death and madness. Two tombs are replaced with alternate versions, and terrifying creatures borne from a mythology of ancient evil gods await players.