Real-time Strategy, but with a twist. That twist is that a compelling story is told along the way. It might be overly harsh to say that RTS games tend to lack when it comes to storytelling, as story is usually confined to pre-mission exposition and post-mission cutscenes. It's kind of a cookie-cutter formula. This game is unique in that it breaks that mold and allows to the story to unfold mid-mission, as you play it, in addition to the pre/post cutscenes (which are beautifully rendered, as is par for the course for Blizzard).