In a similar vein to the developer’s previous games, Amnesia is an exploration-based adventure game played from a first-person perspective. The game retains the physical object interaction used in the Penumbra series, allowing for physics-based puzzles and interactions such as opening doors and fixing machinery. Few in-game objects are operated by toggle; to open a door, for instance, the player must hold down a mouse button and then push (or pull) the mouse, and thus the door, open. This gives the player stealth, allowing them to peek out a barely-opened door or open it slowly to sneak away, but also adds to the player’s sense of helplessness, as it is now entirely possible to attempt to push open a “pull” door whilst danger approaches from behind.
In addition to a health indicator, Daniel’s sanity must be managed. Being in darkness too long, witnessing unsettling events, or staring at monsters will reduce Daniel’s sanity, causing visual and auditory hallucinations and drawing the attention of monsters. Light sources help restore sanity, and if none are available Daniel may use tinderboxes to ignite candles in wall sconces and candelabra, or deploy an oil-burning lantern found near the beginning of the game. However, the number of tinderboxes and the amount of oil available are both limited, and standing in a light source also makes the player more noticeable to monsters. The player must balance the amount of time Daniel spends in light and shadow. Sanity is fully restored once Daniel completes an objective or progresses the game’s story. It may also be restored by staying in the shadows until Daniel passes out, but this leaves him extremely vulnerable to any nearby monsters.
If a monster spots Daniel, it will chase him until he’s out of sight. If spotted, Daniel must flee, as Amnesia does not give the player access to weapons. Daniel must find hiding places or barricade doors with rocks, chairs and other obstacles; however, monsters are capable of tearing down doors in their path and kicking obstacles out of the way, and move extremely fast once they have spotted their prey. Players can also choose to hide Daniel in the shadows, at the cost of sanity. Monsters who lose sight of Daniel will search for him for a time, but will eventually leave and vanish. At several points in the game, Daniel must lure them into destroying an obstacle in his path.
The game recommends playing in a dark room, adjusting the gamma and wearing headphones. It also advises not to play to win.