I won't go into every little feature that the engine contains as that would be unnecessary. Those are some of the highlights. Please keep in mind that I haven't finished this yet, so expect more features and original moves to come. This is a work in progress so keep checking back for updates.
And lastly, comes the storyline. Expect revisions and such as time progresses. The game takes place after Sonic 3. Here's a basic overview.
With the power of the Chaos Emeralds, Sonic was able to restore peace to the planet and destroy Dr. Eggman's Doom's Day creation, the Death Egg. As he finished his job, the Chaos Emeralds scattered to different locations across the planet as they were no longer needed. With peace restored, Sonic and pals could finally relax. 9 years later, the planet began experiencing small earthquakes. The source is unknown.