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 EX (often abbreviated as S.EX) is a hack of Sonic the Hedgehog 2 for the Sega Mega Drive/Genesis by Mr. EX. Its highlights include spring-based layouts like those of Project Shadow 2, new art and layouts, and original music.

Sonic 2 Megamix is the first installment in the Megamix series of hacks by Team Megamix, followed by Sonic Megamix. It was created by Tweaker for submission in the 4th Hacking Contest. It features edited palettes and music.Future plans were to revamp the hack, including moving it to a split disassembly and revamping the level layouts; the former of which has already been completed. It was also to contain various pieces of original music, as well as imports from other games, such as Sonic Advance 2, or Sonic Jam.

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 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 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.

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.