>>140272450NTA
The story would've had Sonic and co seperated after being shot down and having to traverse the Eggman-controlled world (with stuff like national landmarks remodeled in the doctor's image. They would've met up with resistance movements, freed locations and united them into a single army.
During the final battle with Eggman, however, it Argus (the alien god who put the Nocturne Clan into the Twilight Cage) would've appeared. Argus had learned from a oracle/prophet/whoever that he was destined to be killed by a mortal, so Argus put any beings that seemed like they could pose a threat to him into the cage; He shows up because Sonic and co escaped.
Sonic and Eggman team up, a fight with Argus occurs, during which a gate to the Twilight Cage opens, allowing the alien races that were sealed within to aid Sonic, including the Nocturne Clan. By the end, Shade and possibly the Nocturne Clan in general were to remain on Earth with Knuckles.
Then, as a final potential sequel hook, it's revealed that the oracle made up the prophecy, setting up Argus to engineer his own defeat.
In what may or may not be a coincidence, the way the first phase of the Argus fight was to end is the same way that The End is finished off in the Frontiers DLC: Eggman firing Sonic from a cannon.
