Survival horror, to me, is just a term for a dark horror setting (no or little comedy) wherein the protagonists are not helpless against the darkness. There is something out there, and it may be unknowable or it may be explained... but the point is that the heroes involved see the world begin to collapse around them and choose to do something about it.

Resident Evil, Silent Hill, Alone in the Dark... these progenitors of the genre all had one thing in common in my mind. While the world collapsed around the main character, they stood tall and fought for what they loved.