Excellent game, does what its meant to through the great sound, physics, lighting, story and decent graphics.
The game is also a great fps game since it has a good variety of weapons which all have a primary and secondary fire mode and you can upgrade them to further suit your preferences.
The monsters are well animated, and are also varied from the common slasher to the giant brutes. The idea of shooting of the limbs also works well imo since in most games - BOOM! headshot... and thats the end of story.
The boss fights are also well designed since they are totally different from the normal monsters and have different stages.
The graphics in the game are not the best, nor the worst. The textures used arent too amazing however neither are the ones in cod4 when you go up close to them. The lightning however makes up for this, you can see the lighting is very well made along with the shadows.
The physics are also impressive in the game with the zero-g mode, the rag doll effects and just generally tossing arounf objects with the kineses module.
The sounds also works effectively with the visual and is amazing how much of a fright you get when a monsters pops out of the vent and the sound track with the horror music.
All in all the game is excellent since it achieves what its meant to, has excellent sound, decent physics, amazing lighting, interesting story and appealing graphics which make the game a must buy for people who like fps games or horror games