*Starcraft, always fun infesting those silly command centres and breaking massive bases.
Red Alert 2 Yuri's Revenge, One of the few games that I do multiplayer in.
Deus Ex, Quite possibly the best game ever.
Deus Ex Invisible War...just kidding!
Fallout 2: It's like crack. Nuclear crack with mutants, power armour and railguns. My latest character is an evil, slave-driving, prize-fighting gangster porn star who can splatter man and mutant alike with her Gauss Rifle, whilst dragging the only two people in the Wasteland willing to travel with slavers along with her.
Galactic Civilisations 2 and its expansions: Just one more turn before I sleep...ok, just one more tech...ok, just one more planet...it won't let me stop!
The Total War Series: Same reasons as GalCiv, except without the lasers, obviously.