I finally got into contact with Mr. Byte, the former leader of the group, and found out that he lost the ROM file for the game, which turned out to be a hack of Sparkster. But luckily, he still had the VRAM file from the original artist, so I've spent the past few hours and just finished hacking the sprites into a Sparkster ROM, so now we can all see what they originally had in mind :D
ROM link here
Apparently the game was also distributed on cartridge like Sonic 4, but I guess it must have been more sparse since it's clearly not getting re-pirated over and over like that one. I hope to come across it someday since Mr Byte himself can't even recall if there was anything else done like a new title screen or other sprite hacks. And going by their other work, there must have been a title screen at the least.
Well, enjoy it, it's pretty amusing playing as Sonic with a rocket pack.
Edit: Sorry if this shoulda gone in the rom hacking section, just thought given its history it might fit more in general discussion.
Edit2: Also, there may be some palette issues and other problems. Can't say if I did a perfect job or not.