I was inspired by a comment in this Penny Arcade Report article on jarring effects of reality clashing with VR:
"It’s easy to mess with someone who is in virtual reality, although doing so is borderline cruel. Anything that increases the dissonance between what the person inside is seeing and hearing from the game and the stimulus from the “real” world will be distracting, and in many cases disturbing.Why not take advantage of the dissonance? These sound like amazingly immersive tools for a psychological horror game. It sounds a little impractical, but with something like second screen or tablet device relaying instructions to a partner (using a timer or a third person view to ensure the effects are synchronized with the game), you could combine in-game effects with physical sensations at key dramatic moments.
If your brain thinks it’s in an underwater ship, why can you hear people faintly talking? You look behind yourself, but you see only the back of your vessel, although that’s where you hear the voices. Being touched is nearly intolerable for some people after they’ve settled into a virtual world; it is incredibly difficult to feel someone’s hands on your body when you look around and see no one around you."
Imagine seeing an elderly groundskeeper get snatched away by something lurking in the darkness around the edge of your lodge, then later searching his deserted room, and suddenly feeling a gentle tap on the back of your shoulder - you turn around and he's standing there, as if having appeared from thin air, smiling and talking to you like nothing strange has happened since the start of the game. Your character could be walking and suddenly hear a visceral squelching sound while you feel a tugging on your real feet, only to look down and see that the carpet has been replaced by a writing mass of grabbing fleshy fingers. Or perhaps while running away from an otherworldly horror in-game, your partner could be lightly brushing or grabbing at the back of your shirt and pants...or even neck.
The partner would probably need to be careful and remain a safe distance away from the gamer while carrying these out.