Did someone say "games?"
Half life is great, but some of those levels were just too damned hard. It did give me the creeps tho, much like Alien vs Predator but the controls were so outlandish the game was near impossible.
Alice was an incredible game, trippy graphics, slick narration and twisted story line guaranteed to freak someone out. Max Payne is a good one, very creepy, plays like a graphic novel, and has a goofy ending. Another one worth mentioning is Clive Barker's "Undying" with it's nightmarish story and forboding graphics that make even the most avid game player jump.
First person shooter honors for me go with Quake I and Quake 2. Quake 3 is loads of fun if you like running around aimlessly and shooting things (it's a great stress reliever) and Quake 3 TDM and CTF is fun because there is some team work involved.
Next up for first person shooter games would have to be Unreal. My only complaint with Unreal is that the maps, although they are gorgeous, were designed by different people so there wasn't a whole lot of gameplay flow - and there were so bugs in the game as well which, after the 5 millionth try at getting out of a situation, became tiresome to say the least. Unreal Tournament is a lot of fun online and less buggy than its predecessor, but I just never got into it as much as Quake.
I am looking forward to Doom 3 - finally a single player shoot em up game with a decent story line, and incredible graphics, unlike any the game world has ever seen, to boot. Can't wait!