Actually suprisingly so. Replace the slow zombies with super fast aliens and your about there.
I'd call it survival horror, although you get guns with unlimited ammo , so thats not a factor. Your pretty delicate (for a marine) so if you get cornered your a gonner anyway. Plus the things can defend against bullets. Other more powerful weapons have limited ammo. Plus you can upgrade various things by using mod chips.
It's pretty creepy although not over the top creepy. Quite graphic too.
You can make your own stuff by sticking things together. I need one more item and I've completed a lightning gun :D
Lots of Fallout References scattered around. Voice acting is top notch and the storyline is really interesting.
It's not one of those 90+ games(more like 80ish). But for