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 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 Dimps Edition is a hack of Sonic the Hedgehog 2 by Spanner. This hack attempts to mimic what Sonic 2 may have been like if it were created by Dimps. This means incorporating many features found in Dimps games such as random speed boosters. This does not include features common in most modern Sonic titles with the exception of a homing attack. The hack was discontinued due to various reasons and there was currently no intention to return to it, except that somebody else now has the source code and is intending to finish off the job. Version 1.5 was uploaded to fix some reported bugs.

Sonic 2 Recreation is a hack of Sonic the Hedgehog 2 (16-bit) by redhotsonic. It sports an ASM overhaul, multiple characters, new zones, a new boss, a new DAC driver that supports many different sound features, new zone art.

Sonic 2 Retro Remix is a large-scale ROM hack of Sonic the Hedgehog 2 for the Sega Genesis / Mega Drive, created by Thorn and DNXDelta. The goal of the project is to create a 2D Sonic the Hedgehog game that requires exploration to progress, as well as the requisite platforming and sheer speed. A mission system akin to those of the 3D Super Mario games is implemented as the means of progressing from one level to the next. Missions involve earning Chaos Emeralds in scavenger hunts, boss battles, speed runs and score attacks; most require learning each level's ins and outs, instead of just finding the easiest way to the goal.

Sonic 2 Secret Rings Edition is a hack of Sonic 2 by MainMemory. It features no new art or level layouts, and few new features, instead adding replayability to the original game by adding various missions that you can attempt to complete, although there are several levels where completing certain missions is impossible, and some levels where it is impossible to lose.

Sonic 2 SMTP is a hack of Sonic the Hedgehog 2 made by SMTP. The hack is an ASM/Layout hack with a couple of new features.