When you idly walk around the mansion in REmake and suddenly a Crimson Head stands up.
Also, one moment that completely terrified me was in Resident Evil 4 when you enter the tunnels in chapter 4. You just roam around in an empty area with no enemies and the game lets you search hidden items a bit, when suddenly a loud noise happens like a metal grid or something getting smashed open and footsteps start to come at you. And those footsteps are FAST, I tell you, and they get louder and lounder but you see no monsters so you start to think that something invisible runs straight at you. But nothing happens, no monsters, it was all just an illusion. I was scared as hell.
Gameplay > Graphics
Substance > Style
Art Direction > Realism