Mighty The Armadillo Game
This is one of the earliest Sonic rom hacks ever, with a new character and a modified Green Hill Zone.
Sonic 2 Dimps
enables level selection and homing attacks against adversaries while in midair. A few new foes, some new music, and some minor changes as well.
Sonic 3 And Sally Acorn
Sally Acorn can be controlled in this sega rom hack in place of Sonic. She is slower than Sonic and unable to perform spin attacks, although she can slide, shoot lasers, and use scan mode to reprogramme Eggman traps and other machinery.
Sonic Scene Creator v2
Create the ultimate Sonic the Hedgehog scene in this upgraded version of the original Sonic scene maker!
Sonic the Hedgehog 2 GG
The Game Gear version offers harder gameplay in tighter spaces and a different soundtrack as well.
Sonic Anniversary
You can spin dash if you choose anniversary mode. Additionally, there is a secret area with jukeboxes someplace.
Sonic 30 Day Challenge
A double-jumping Sonic hack that is really well done. Only until you acquire an Emerald monitor are wall breaches feasible.