My guess is that it will probably still run within the starcraft 2 engine- but since it's going to be included in the Starter Edition, it's essentially it's own free to play game.
Either way it certainly looks like they're working to make this more than just some mod :)

Sixen ModeratorThought this was interesting, they just created a job posting for All-Stars Lead Designer. Perhaps it'll be a AAA game right off the bat, rather than running through SC2? Seems like they're pushing to make it a legitimate product more and more as time passes... Could also be the reason why we haven't heard anything in so long, ;).
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