This game is too hard. It's so frustrating that you can't even finish it after so much time. It;s great, but too bad that it has some issues. Firstly, the enemies are too damned good. They can kill you instantly and re-spawn when you return. I didn't even finish because I got to a part too frustrating: no more ammo, the weapons break and can't be repaired because I've no nanites, well, I'm in a mess here.
The game is great because the story is great. You're the only survivor and you've got to do your best to survive and get out of it. To do it you can upgrade almost everything you can use. The music is entertaining and in accordance with the action. The adversaries are scary and the noises they produce are horrifying. You won'tr forget them for a long time.
I hope one day I shall finish it, but it's damned frustrating.