God. That sounds so pathetic. Yeah, I've gotten nightmares from computer games. Two of them, actually. The first one to give me nightmares was System Shock II. The Many creeped me out that fucking much. Then I played Thief a lot later. I'd played the demo to death, got the game and loved it. It's pretty tense, but the Return to the Cathedral is just the worst. You're sitting in the shadows hoping a grinning skeleton dressed in the clothes of a holy man won't find you. He's making a noise that sounds like the rattling of chains and he's screaming about how his soul is burning and that you should stop hiding and join him in flames. If he finds you he'll make good on his promise and quickly end your life with a few sword blows. If you move he might see you, but if you stay where you are he will probably find you. And this cathedral is crawling with the fuckers. Any sound that's vaguely like the chain rattling still makes me a little nervous.
Then there's the part where you're running along the rafters of the cathedral while they run back and forth beneath you like hounds waiting for you slip and fall. That's the part I dream about: balancing while the demons scream at me from below.