Dead Space 1, the original. I recently realized I own it on the EA account I forgot having made and figured I'd take a look. I'm partway through chapter 3 now. The game really shows its age graphically, the ragdoll physics on the many corpses lying around keeps glitching out, and if the game is actually trying to be horrifying I feel a touch more subtlety would have been called for. It often feels more like a haunted house than something that's supposed to seem like a real place.
That being said, the combat is satisfyingly visceral (the gimmick of focusing on cutting off limbs was a very good idea), and tech limitations aside both the art direction and sound design are very solid. The times the game actually manages to be unnerving is almost always due to the tension of hearing the monsters in the walls but not being able to pinpoint its location.
Overall, I'm not exactly in love with it but I'll probably play it all the way through.