Sonic 1 - Comet Edition v2.1 is a hack based on sonic 1 made by B. CasaisIt features a major focus in level design with a nice amount of secrets and alternate paths, some graphical and musical changes. It's my "second" attempt at hacking. •Zone Features• Green Hill ZoneNew music;New pallets;New background; Complete new layout.• Marble ZonePlace holder music (Scrap Brain);New background and title set;Complete new layout.• Spring Yard Zone - Experimental/UnfinishedComplete new layout for Act 1 only (experimental);New background;Pallet changes.The rest of the zones remains the same as the original game.• CreditsShitty Person: For S. Speedway Past - Sonic 1 SMPSGamma V: For Sonic 2 (SMS) - Boss (16-bit) SMPSRazor and Zenon and RedHotSonicSSRG and friends: Overall feedbackNeoFusionBoxGanacchii:

Sonic 2 Adventure Edition is a hack of Sonic 2 by MainMemory, based on Sonic 2 Adventure Control. It transplants various gameplay mechanics from Sonic Adventure to Sonic 2.

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.