In a similar vein to the developer's previous games, Amnesia is an exploration-based adventure game played from a first-person perspective. The player has no access to weapons, and they must use their wits to avoid or hide from enemies. The game also retains the physical object interaction used in Penumbra, allowing for advanced physics based puzzles.
The game casts the player in the role of Daniel, who awakens in a dark castle with little or no memories about himself or his past. All that he can remember is his name and that something is hunting him.
The game's story seems to be, at least in part, inspired by the short story "The Outsider". This makes sense when considering the frequent homages the developers make to the author H.P. Lovecraft and his works. Even the engine which powers all Frictional Games's titles, the HPL Engine and the HPL Engine 2, bears the aforementioned author's initials.
It is possible to create custom stories for Amnesia that can then be loaded in the game. Various tools for the HPL Engine 2 have been released that allow the creation of own levels, models, particle effects and materials. Game logic can be implemented in a scripting language similar to C.
Work began on the game while Penumbra: Requiem was still being developed, with the company working on both projects at the same time. Amnesia was first announced on November 13, 2009 with the release of the games website and a game trailer. On February 5, 2010 it was announced that the game had reached the alpha stage of development on all platforms. Two weeks later the developers released a new Teaser trailer showing actual game-play footage, as well now allowing for pre-orders. Also revealed was that the game is currently in-testing on all three platforms and the game would be released simultaneously for all of them in August 2010. This was later rescheduled, and the game was then expected to have a September 8, 2010 release. It was announced on August 27, 2010 that the game had gone Gold. On September 3, a demo for all three supported platforms was released containing selected parts of the gameplay and story. The game was then successfully released on September 8, 2010.
If the game reached 2000 pre-orders by May 31, 2010, Frictional promised it would release extra content for the game. The goal was finally met in early May, after the pre-orders were offered at a discount made available until May 31. This was done due to the success of Penumbra: Overture as a part of the Humble Indie Bundle. The extra content was revealed to be commentary, they explained in the comments section of the same page that it will function similar to Valve's commentary system that began in the Half-Life 2 series.
Amnesia has received generally positive reviews with consistent praise given for the ominous atmosphere and horror elements, with Rock, Paper, Shotgun's [|John Walker]] going as far as to say that "I think it is safe to say that Amnesia is the most successfully frightening game to have been made".