The Artificially Prolonged said:
Stalker Clear Sky after going through the red forest at night *shudders* last time I play that game with my headphones on at night.
Oh, I did that in Shadow of Chernobyl, with absolutely no background on it. No knowledge. And I was playing with the Stalker Complete mod, so it looked even scarier. I got about 15% in, killed a guy, grabbed his really nice sniper rifle, and just fucking ran away back to the Bar.
That didn't really give me nightmares, but what did was the tunnels in the first game, Agroprom Underground, I think, with the first bloodsucker encounter. I'd never heard of them before, and then, BAM! I was looking away, and it grabbed me from behind, and started to, well, suck my blood. Didn't even know what got me until I died. Nearly shit my pants. Couldn't sleep well for a month.
Also, when I was like 4, I got really scared from watching my dad play Duke Nukem: Manhattan Project. Don't really know why, though. Pigcops, I think it was. Again, don't know what actually scared me about them.