Ok, in no particular order;
1: Renegade. Liek duh...
2: Star Wars - Republic Commando. If Renegade had this level of quality in it's single player, I would never have stopped playing.
3: Age Of Empires 3. As much as I despise MS, this is quite a lot of fun, especially when you've got two brothers, enough PCs and plenty of time.
4: Starcraft. Well, I think we all know what SC is, probably the only game with a 10K game count, after almost 10 years. Wow. Is also a lot of fun doing team melee with elder brother, we're getting too good.
5: Unreal Tournament (Pick a version, any version...) Fast and fun. I'm the best out of all my brothers, must be all the Renegade I get in.
Hehe.