Without any doubt, Star Craft has to be one of the best real-time strategy games available today. In the sequel, we will see the return of the three original races although StarCraft 2 is planned as a trilogy of sorts with Terran: Wings of Liberty, Zerg: Heart of the Swarm, and Protoss:

Legacy of the Void being released separately. The only downside is having to buy the 3 games separately. But then again, this is Star Craft and it could be worth the money. I expect this to be a highly polished game with an emphasis on addictive multi player.