At the risk of sounding like a parrot I feel compelled to say Halo.
Admittedly the concept was original, and I give Bungie full credit for plugging the Halo series for all the money it could spew out. To give an analogy, because I've grow slightly obsessed with them(analogies that is).
Halo is the new guy to come to school, who no-one has ever met before. He's good at telling jokes and at first you get everyone laughing hilariously, so more and more people start listening to him.
His jokes start to dry up but he has a great idea, redress the jokes with a modern slant to make them more interesting. Pretty much everyone still thinks their funny, but a few people start to see where this is going but laugh along because the joke still sound relatively good.
Time passes and the novelty start to ware off again, so he tries the same trick the jokes look even better but when people start to look close and see the same jokes dressed up again. But a lot of people still like it so most go along while some denounce it completely. But as this kid keeps repeating him the clever ones break out the baseball bats and clobber him to the consistency of minced meat.
In this case Bungie make a mould of an RTS and press the minced meat into it, this is at a point where the meat is starting to rot and excrete a strange juice, make a strange smell and everyone's beginning to think that Bungie are going a bit blind and lost their sense of smell.
Now everyone looks back and they start to think, hey that wasn't really that good was it. Now Bungie are chucking half-baked sequels to sedate the clamouring mob and distract them.