http://store.steampowered.com/sub/32031/The Penumbra bundle is also on sale for $2.
If you enjoyed Amnesia, I highly recommend it. Game can run on a potato PC and still holds up pretty well graphically.
Honestly, I feel it's still Frictionals best game. Where Amnesias horror came from the spooky monsters and creepy dungeons, Penumbra uses isolation as a core theme when trying to depress you. I don't think I've ever felt more "alone" in a game before.
Both games rely heavily on the mystery aspect, too. Amnesia was about, well, amnesia. The mystery was figuring out who you were and how you were involved with the mansion and the dark creatures that inhabit it. Unfortunately, it tapers off around the second half of the game where you start learning the truth of who you are and are forced into a really lame vengeance plot.
Penumbra sets up the entire plot from the get-go though, and almost has a sense of adventure when starting off only to come to the realization that going off on a quest to find out what happened to your missing father isn't all it's cracked up to be.
Seriously though, buy Penumbra. It's in the same style as Amnesia, but with a more interesting modern arctic setting, better puzzles, and a better story.
https://www.youtube.com/watch?v=vDsEQfzvq40# 
