I know I'm waaay behind the curve on games, but still...
I think part of what makes this game so damned creepy is because the shells of the once-human walk around saying stuff they said before they died. Sometimes, their last terrified words; sometimes, just...mundane stuff they said while alive.
It's like that Dr. Who episode with the dead people's suits walking around & saying stuff like, "Hey! Who turned off the lights?" -- just, times a thousand.