Starcraft II: Wings of Liberty
I won't get into details, but this is definitely one of the best RTS games out on the market. They've captured all the fun of Starcraft Broodwar and added in features that were missing. Sure, some of the features like LAN are gone, but most people have broadband internet nowadays anyway. Also, I will say that the transition from Starcraft Broodwar to Starcraft II was much better than the leap from Halo CE to Halo 2.
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