I thought this was a pretty neat video: [media]https://www.youtube.com/watch?v=7TuNELgWv-w[/media] It starts out looking like a regular sonic playthrough then it cycles the characters in every stage, looking like a hack where the character changes in every stage. Most of the hacks seem to be hosted on the wiki.
It's different plays edited together, neat! Saw how each act starts with a score of 0 but of course that'd be hard to put together as a consistent thing.