Eternal Darkness: Sanity's Requiem is a 2002 horror game developed by Silicon Knights and published by Nintendo for the GameCube. It was produced and directed by Denis Dyack. The game follows the story of several characters across a period of two millennia and four different locations on Earth, as they contend with an ancient evil who seeks to enslave humanity. The gameplay distinguishes itself with unique "sanity effects", visual and audial effects that confuse the player and often break the fourth wall.