🎮 Play Sonic the Hedgehog (USA, Europe) [Hack by Stealth Rev 1] (~Knuckles the Echidna in Sonic the Hedgehog) Online (Sega Genesis)

Knuckles the Echidna in Sonic the Hedgehog — usually just called Knuckles in Sonic 1 — is a Sega Genesis ROM hack released in September 2005 by Stealth (Simon Thomley, later a co-director of Sonic Mania). It rebuilds the original 1991 Sonic the Hedgehog around Knuckles instead of Sonic, giving him the moveset he’d later get in Sonic & Knuckles: Spin Dash, Glide, and wall climbing. At the time, a working Knuckles-in-Sonic-1 hack was considered the “Holy Grail” of Sonic ROM hacking — a palette clash had kept Sega from ever doing it officially, so locking the original Sonic 1 cartridge onto a Sonic & Knuckles cartridge only ever unlocked the bonus game Blue Sphere. Stealth solved the palette problem by conforming Knuckles’ sprite to Sonic 1’s existing colors rather than the other way around, and built the hack on one of the first full split disassemblies of Sonic 1’s code — groundwork that would later feed into his own official Sega remakes.

How to Play

The goal is the same as Sonic 1: clear each Zone’s three Acts, collect Rings for protection, and grab Chaos Emeralds in the Special Stages. Knuckles controls like his Sonic & Knuckles self, not like Sonic:

• Move — Arrow Keys
• Jump — S, X, or Z
• Spin Dash — hold Down, tap the jump button, then release Down to launch
• Glide — press jump again in mid-air, then hold a direction
• Wall Climb — glide into a wall to start climbing it; press jump again to hop off
• Start / Pause — Enter

Tips

• Knuckles’ jump button doesn’t act like Sonic’s spin-jump — a second press in the air starts a Glide, not another hop, so mashing it across a gap sends you sailing into a wall instead of clearing it.
• Getting Super Knuckles takes more than the seven Chaos Emeralds: this hack also gates the transformation behind a code entered on the title screen.