When "Sonic and Knuckles" was released, fans were disappointed to find that "Lock-On Technology" didn't apply to Sonic 1 in the same way it did with the second and third games. Some speculated that there were technical concerns. "Knuckles the Echidna in Sonic the Hedgehog", known also as "Knuckles in Sonic 1", is the result of longing for this lost opportunity, and the desire to prove that, from a programmer's standpoint, this was not impossible. I have reverse-engineered and adapted assets and code from "Knuckles in Sonic 2" to give Sonic 1 a complete facelift in this regard, featuring all things "Sonic" changed to "Knuckles", including perfect replicas of his signature moves, minor tweaks to prevent him from getting stuck, and even a few bugfixes.
Released in 2005, this mod proved highly popular and was regarded as a major technical achievement for its time and for a fan with no access to the original sourcecodes, which led to it quickly finding its way onto many sites, and otherwise being reviewed and praised by others. By now, there's no escaping the fact that it's out there.
The file is provided here for historical and novelty purpose. If you, for some reason, do not own a copy of the original Sonic the Hedgehog, please be respectful and support Sega by purchasing one before playing this modification. This is not the game as it was originally released, but is still based on their work, and was meant for those who have already played the original game to death.