Tony Ponce pointed out this video, using words such as “spiffy” and “kick-ass” to describe it. I think you’ll find that he is not wrong.
It’s a fan-created project attempting to recreate the final zone in Sonic & Knuckles with a few adjustments to set the scene and an unfinished conclusion. The creator, a YouTube user called “Major Dump,” says that he started on the project over a year ago but got burnt out working on it while holding a full-time job as a professional animator.
Good God damn, it’s pretty. I hope he comes back to it someday because this is amazing work.
Doomsday Zone Part 1 [YouTube]