I've mentioned these before and I'll do it again:
- Exanima - Read about the features. This one is more impressive than the screenshots make it look (at least for me).
- Lunacid - I love the visual style and atmosphere of this. I also enjoyed Lost in Vivo by the same developer.
- Praey for the Gods - This one is for anyone who's looking for more games like Shadow of the Collossus.
- The Upturned - A cartoony horror-comedy game with a great sense of humor.
- Withering Rooms - The story is interesting and the atmosphere is great.
- Your Spider - This one is possibly my favorite indie horror game.