Lots of games claim to be Survival Horror. Outlast is just about the only one that truly is. The reason that is? Simply because throughout the entire game, your only choices are to run and hide. At no point in the game do you even have the option of fighting back. You make it through the game based on timing and your choice of hiding spots. Otherwise you die. Horribly. Over and over.
The story isn't particularly original to be honest, not that it really needs to be as well-executed as it is. You are Miles Upsure, an investigative reporter looking into a tip that a huge corporation is conducting illegal human experiments on the patients of a local asylum. In order to investigate this tip, you go and break into a (as far as you know), still operating asylum. It seems that all hell broke loose just prior to your arrival though and your investigation quickly turns into a nightmare of simply trying to survive.
Along the way you encounter more than a few psycho's that want you dead, and a few that lead you along by the nose, trying to show you what was going on. Eventually you find out all about what horrific experiments were being conducted and the end result of them.
The controls are good, if somewhat specific. I died more than a few times as I tried to shut a door behind me in the face of an enemy and ended up shutting the door in front of me instead, but that's not really too big of an issue.
The environments are excellently done, with the use of your camera's night vision absolutely imperative to your survival and making everything even creepier with it's green tint. There's nothing really beautiful here though. Every setting is meant to creep you out, if not outright disturb and horrify you. They all succeed.
If there is one thing that brings the game down, it's the fact that it's so short. If you don't get stuck, this could easily be played in three hours or so from start to finish. I'm also a little disappointed in the plot twist at the end, even though the game does a very good job of making you think one thing through most of the game and then turning it into something else entirely.
So if you enjoy games that are high tension and WILL scare and disturb the crap out of you, play Outlast if you can. If you can't you can watch a few others play it on YouTube. It's certainly worth watching if you can't play it.