1UP's Luke Smith puts on his tinfoil hat and speculates that Bungie might be returning to the real-time strategy genre. If memory recalls, Bungie's first post-Marathon title was the 3D strategy title Myth: The Fallen Lords. And Halo was originally going to be a strategy game, as revealed on the Halo 2 Limited Edition DVD. Smith connects a few key Bungie members to Texas-based Ensemble Studios (Age of Empires) and concludes that they might be working together.
It's all massive speculation, although more Halo titles seem very likely. As an RTS, though? We'll hold our breath, hoping Bungie can break us from our real-time cynicism; in the meantime, mourn the passing of Halogen with a trailer for the mod, embedded after the break.