Even though I've learned not to see games as something productive, ever, I think I have some suggestions.
PC: Aliens vs. Predator.
A first person shooter where you play as Marine, Alien and Predator. It may not have the newest combat features, but it's a very solid shooter, it's fun, it's beautiful, it's unique. Playing as an Alien is amazing. The Marine campaign is so scary, especially on the hardest difficulty. Predator owns too. Oh, nice music too (if you can find a copy with the music CD).
A must-play if you're a fan of either movie series.
PC: Myth & Myth II.
Great fantasy strategy games. They're pretty slow games in which you can't build. You're giving a set of units per level. If your units survive, they'll come with you to the next level, with more experience. It uses 2D sprites on a 3D map and it works really well. With the newest patch it even looks kind of pretty, especially for 10 year old games.
The gameplay is very satisfying. I really liked the story and the atmosphere. Just stay away from Myth III, which plays terrible. Oh, Bungie made Myth 1 & 2.
