Sonic 2 Delta is a groundbreaking series of ROM hacks by famed Sonic scene member Esrael Neto, which restores several deleted levels and prototype elements to Sonic the Hedgehog 2 for the Sega Mega Drive / Genesis. Various features of Sonic 2 Delta, common across the series despite the existence of several versions/branches of the hack, include the use of art and music from the betas and Sonic the Hedgehog and re-implementation of badniks that had been removed from the final game. The level order of Sonic 2 Delta is also similar to the original intended order, rather than that used in the final version. The main version of this hack is entitled Sonic 2 Delta and was based upon the Simon Wai prototype, before version 0.24 transferred the codebase to 'revision 2' of Sonic 2 from Sonic Compilation. More information on the various lineages and their history is detailed in the section "Other versions" below. A hack similar in concept, called Sonic 2 Long Version, has been released by another hacker, Sonic Hachelle-Bee.

Sonic 2 Millennium Edition is a palette and layout hack of Sonic the Hedgehog 2 for the Sega Mega Drive/Genesis by Striker.

Sonic 2 Revamped was a heavy modification of Sonic the Hedgehog 2 created by Irixion. This mod first started out as a layout hack, a test of skill, and what Irixion could do. At the time, it didn't have a name, but after seeking for someone who could help, Tweaker suggested the name Sonic 2: Revamped, and it stuck ever since. It eventually grew into a few close friends helping out, and the project grew into realizing Irixion's vision of the perfect game. After major setbacks and a core crippling incident, the hack was ultimately scrapped.

This is a hack based if the original Sonic 2, that has been in the works for quite some time. It includes 4 characters to choose from all with different moves that fit them. Every level in this demo has had a background change, along with new music in each act. Layout changes (Knuckles has some of his own) and much more...Story: Shadow is back and teams up with Robotnik...Credits:Project Leader: JoenickROSLayout: NeofusionBox, JoenickROS, Markeyjester, Electroball, Shockwave, BakayoteMusic and Sound: JoenickROS, Bakayote, KCEXESounddriver: Flamewings S3K driverArt: Blazer, Bakayote, KCEXE, AsuharamoonMinor Coding: JoenickROSMajor Coding: Shockwave, Varion Icaria, RalakimusBeta Testers: Mike B Berry, ThomasSpeedrunner, Bakayote, Shockwave, Varion Icaria, NeofusionBox, King of HeartsNatsumi: Credits SequenceSpecial Thanks: Shockwave, and Varion Icaria, without them, I might have not been able to fix some of the coding bugs.

Made by Team AE Sonic 2 Advanced Edit features 7 entirely new zones, each full of unique enemies and with a boss whose gameplay varies depending on which character you play as. Playable characters are Sonic, Tails, Knuckles and Amy. Furthermore as bonus content, the hack features the 5 zones from the 2008 release, brushed up to be fully playable. Upon completing the 7 main zones, you obtain a code to access the level select from which you can play the bonus zones by selecting "South Island 1".

Sonic 2: Aluminium Edition is a hack of Sonic the Hedgehog 2 for the Sega Mega Drive/Genesis by Dr. Eggfan. It doesn't feature any ASM content nor new layouts, it's pretty much Sonic 2 with a few new visuals, and for some reason completely different names for the same zones. There's also a partially restored Hidden Palace Zone in there.