While I am tempted to call this the scariest game EVER, I'm aware that I am prone to hyperbole and in fact that might be an honor best reserved for Amnesia 2: The Remembering (That's not a real game -Ed.)
It's at least the scariest game of 2010 though and that's enough for me. Like all great horror movies, this game is 99% atmosphere and 1% getting your face ripped off by unspeakable horrors. The gameplay is typical exploration and solving puzzles of the physics and conventional varieties. It's not outstanding in that regard, but it keeps things moving along and gives you a reason to explore the twisted catacombs.
This is a great game by a smaller independent developer, and proof that you don't need billions of dollars to make a fun game. It's a shame it's only on PC, I'd love to see it show up on XLBA or PSN some day as DLC.
If I had one complaint I'd have to say that they don't mix up the scares quite enough. Usually you activate something, and hear the noise of a monster approaching while you cower in a closet or behind some barrels. The level where you get chased through the sewer by a water monster is awesome though.