While the notion of Sonic being on a Nintendo console isn't shocking in 2023, back in the '90s, it was unthinkable – which is why the only 'port' of the game was an unofficial bootleg by the name of Somari the Adventurer.
Developed by Hummer Team and published by Ge De Industry Co. in 1994, this unlicensed title took Sonic's core gameplay and transplanted it to the NES. It would later be redistributed under a series of different names on the Hong Kong pirate market, including Sonic 3D Blast 5, Sonic 5, Sonic & Knuckles 5 and Family Kid.
As you might expect, the quality of the game isn't all that impressive, which is why modern-day homebrew enthusiasts have taken it upon themselves to improve it. Coder the jabu started the ball rolling, and since then, this noble venture has attracted the attention of other contributors – including Terwilf, who has just released an 'unofficial continuation' of the project.
"This hack greatly modifies a large part of the game’s resources to provide a better experience, adding a new soundtrack, redesigning levels, renewing the graphics, and introducing a series of new elements and mechanics, among many other features," reads the game's page on Romhacking.net.
The end result is very impressive indeed, as you can see from the video below.