That Earthbound... the scene with the boy and the cliff and the thinking - easily and exclusively, especially because of the "out of nowhere" factor. That was disturbing, and I played it blind. I never stopped getting the feeling that that character wasn't that character anymore after that. Scary stuff.
I guess the ending too, but I don't really think it's the same. Plus that scene is generally unknown to people who haven't played, where as the ending people spoil all the time.