A poor monitor + Alien Vs Predator 2 = Scaryness Omega.
I'm not even kidding, because of the crapness of my monitor I had trouble seeing even in normal light. The first part of being a Marine, crossing this outdoors bit to get to the base, I could just barely see what was five feet in front of me and no more.
I crawl around the base like a near-sighted old man, nearly walking into the skinned corpses of scientists and other marines. There's this constant beeping on the motion detectors which I realise, after 15 minutes of terror, is the movement of a chain. Finally, after being spooked by all matter of bugs, I manage to get inside. Amongst the corpses I finally find a station I can use.. then the screaming begins.
The door I had just came through locks down and I hear a fierce pounding outside, on top of screams and radio chatter. The door
bulges towards me, I'm training my rifle at it and shaking in my computer chair.
Then the ventilation shaft on my left bursts open and Aliens start pouring into the room.
I fight my way through the shaft, unleashing everything I've got, occasionally just firing of a grenade because I'm too scared to think. After being attacked half a dozen times I finally work my way out.. into pitch black. The motion detector is ringing off the chart, my health is in the red, and I'm running, firing into shadows, for the light at the end of the corridor.
I manage to spot a couple running towards me as I run backwards, I fire a grenade that nearly takes me with them and don't even care.
The light. Except it isn't escape, it isn't sanctuary. It's just one light that didn't burn out with the rest. I'm stuck in the middle of enemy terriotory, the screams of creatures I can't even see echoing in my ears, and I don't know how to get out.
And the click of talons on metal approaches once again.
. . .
That was the most I've ever been scared of a computer game.