The game's setting is centered around a mansion in Rhode Island, the home of the protagonist Alexandra Roivas' grandfather and the mysterious book known as The Tome of Eternal Darkness that Alexandra finds there. It is presented in a third-person perspective in which the player must navigate a number of locations as 12 characters spanning different time periods. The game utilizes unique "sanity effects" to enhance the gameplay.
Though not a commercial success, Eternal Darkness was widely praised, even winning the Outstanding Achievement in Character or Story Development award at the 6th Annual Interactive Achievement Awards, presented by the Academy of Interactive Arts & Sciences.