I found this game very hard, but maybe I gave up too soon. But the bit I got to was I was in a room, like a laboratory or something and then I was sealed in and had to fight and kill a certain number before the door opened. Well my problem was that I had so little ammo that I didn't have enough to really do anything.
Only option I had was to keep going and get annoyed not getting anywhere, start again or give up. It's only one of two games i've ever given up on.