This is a ROM hack of Sonic the Hedgehog with the title character replaced by Knuckles the Echidna, complete with his signature ability to glide as well as the usual spindash. Everything else is unchanged. If you haven't seen Sonic the Hedgehog completed before, you may wish to do so before seeing what a character with a more advanced move set can accomplish.
ShiningProdigy9000, rodonic01, WST, and marzojr all work together to speed through the bonus stages to collect all 6 Chaos Emeralds and zip through the rest of the stages as fast as possible.
There is also a run of different ROM hack of the same game that replaces Sonic with Tails.
There are alternate encodes where the camera is hacked to stay focused on Knuckles as much as possible.