White Night is a total conversion mod for Amnesia: The Dark Descent; and focuses on mostly storytelling.
This is an old-school type thriller. Although it's not mainly a horror game, it'll have its scares; and will offer beautifully designed levels in an old-fashioned asylum with various puzzles to solve. You will discover what happened to David, what he did, and why the mod is called "White Night". But, how are you going to be sure what's been told you, or what you see is the truth?
Amnesia: The Dark Descent 1.2 patch (Justine).
At least 700 MB of free space is needed.