Eternal Darkness: Sanity's Requiem is an action-adventure psychological horror game developed by Silicon Knights for the Nintendo GameCube. Released in 2002, it is known for its unique sanity effects that play mind games with the player as the characters' sanity meters deplete. Players navigate through different time periods, controlling various characters as they confront eldritch horrors linked to ancient deities. As a mixture of exploration, puzzle-solving, and combat, the game's innovative mechanics and Lovecraftian themes have won it critical acclaim.