10. Outlast
Dubbed by many journalists as one of the scariest games of all time, it's surprising how this game was overlooked by many. Well, maybe it's because it was only released for Microsoft Windows. It's not as long as a typical AAA game, but it packs more scares that most of the recent "horror" games I've played recently.
In my opinion, Outlast is like a combination of Fatal Frame and Condemned set in an Asylum. You cannot fight because the only thing you can do is hide. Players also have to battle the darkness using a video camera's night vision function, but be careful not to use up all the battery.