When I said I'd make another one of these sometime in June, I had no idea it would be June 2009!
5. Sid Meier's Civilization IV: Standard turn-based 4X.
4. World of Warcraft: MMORPG. Still playing. I'm pretty sure I'm supposed to be more than level 56 by now, but I guess I've always sucked at levelling.
3. Garry's Mod: Source Engine sandbox construction. Pretty much Half-Life 2: Deathmatch, but you can build contraptions!
2. Warhammer 40,000: Dawn of War: Dark Crusade: Sci-Fi RTS. A standard modern RTS, but excellently made to resemble the WH40K tabletop game!
1. Sins of a Solar Empire: 4X RTS Space Opera! (That's like three genres added together >.>) You start with a single planet and must eXplore the nearby galaxy (one or more star systems), eXpand to those planets, eXploit their resources, and eXterminate the enemy! All in real time! And with spaceships and explosions. Can't beat the spaceships and explosions.
Again, if you'd like to try WoW, email me so I can refer you >.>