There are a few great articles about scary games and game moments in history. I’ve linked them up here:
Joystiq: http://www.joystiq.com/2011/10/31/joystiqs-favorite-unintentionally-scary-games/
Lazy Gamer: http://www.lazygamer.net/general-news/retro-monday-horror-games/
Destructoid: http://www.destructoid.com/the-scariest-videogame-moments-of-all-time-214758.phtml
A quick list of mine include:
- Half life headcrab attack. Almost every one, but the first time you see them is definitely creepy.
- Aliens vs Predator 2, in the Hive during the Marine portion of the game. That scared the crap out of me.
- The introduction of the Flood in Halo.
- All of Dead Space.
- Limbo, the spider and the ambiance in general.
- Bioshock, the scary violin music, and the people sculptures.
- Introduction to the Berserker in Gears of War.
- Beginning of Resident Evil. Thats all I played, and that was all I needed to back then.
The picture is from the Darkseed game, which I never got to play. It looked very creepy.