User Name:
Game: Clock Tower
System: SNES (You're gonna have to get the translated ROM, don't worry it's fairly easy to find. PM me if interested)
ESRB Rating: M (I think, Japanese stuff yunno....)
Reason: Clock Tower was influential in that it played out like a true horror movie. The main character is a young orphan girl with absolutely no means to defend herself, therefore making hiding and running your only options to survive. As a matter of fact, where you happen to be chased plays an important part in how well you understand the story (in my first playthrough I understood very little besides "I need to run the f*** away!" because the villain just so happened to chase me away from areas that had background information on the story). Perhaps one of the absolute best and realistic (considering the limited abilities of the protagonist) survival horror titles out there.
Oh and multiple endings. Gotta love em.