Halo Wars was, without a doubt, the killer title for the Xbox 360. None of the other last generation games stood a chance. However, around the game's launch, Ensemble Studios shut down. The game was supported by Robot Entertainment, but hopes for a (much desired) second installment were slim.
At Gamescom 2015, Microsoft triumphantly announced that Creative Assembly was working on Halo Wars 2 (launching fall 2016; on Xbox One and Windows 10).
Jokes aside, I did have fun with Halo Wars, and a sequel makes me happy.