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 toSonic 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 3D Blast (Japanese: ソニック３Ｄブラスト, Hepburn: Sonikku Surīdī Burasuto), also known as Sonic 3D: Flickies' Island (ソニック３Ｄ フリッキーアイランド, Sonikku Surīdī Furikkī Airando), is a 1996 platform video game developed by Traveller's Tales and Sonic Team, and published by Sega for the Genesis, Saturn, and Windows. Part of the Sonic the Hedgehog series, the game abandons previous Sonic games' side-scrolling style in favor of isometric gameplay, making use of some pre-rendered 3D models converted into sprites. The game features creatures known as Flickies, which first appeared in the 1984 arcade game Flicky. Controlling only Sonic himself, the player's goal is to collect Flickies and carry them to safety, periodically sparring with the series antagonist Dr. Robotnik, who is imprisoning them within robots. The game was developed alongside another Sonic game for the Sega Saturn, known as Sonic X-treme, which would end up cancelled. While 3D Blast was initially created for the Genesis, which had already been discontinued, Sega also commissioned a port for the Saturn. The Saturn version of 3D Blast was developed as a backup plan in case X-treme could not be released. Both versions of Sonic 3D Blast received mixed reviews from critics, who generally disliked its isometric gameplay but praised its visuals and music. The game was later ported in 1997 to Microsoft Windows computers and released on numerous Sonic themed compilations and digital distribution platforms.

Sonic the Hedgehog hack made by By Narcologer fully remade zones: Paradise Coast (GHZ), Border Fort (MZ), Dangerous Pit (LZ) and Robotropolis (SYZ) with new music, layouts, graphics and some new chunks. characters: Sonic, Mighty and Metal Sonic. Sonic can perform spin dash and peel out, Mighty can perform jump dash and double jump, Metal Sonic can only to spin dash but also he can't drown.Because 3 characters (and there will be more in future releases!) are too many for title screen I made a simple character select menu.A lot of new sprites.New Sega logo screen.And lots more!Credits:Programming: Narcologer, Vladikcomper, Sonic2010, EsraelNew level art, new chunks and layouts: NarcologerSprites: Narcologer, The Spriters Resource, SCAA, Lone DevilMusic: Ivan YO, STD, Nineko

Sonic Classic Heroes is a ROM hack for the Sega Mega Drive / Genesis that is the result of a collaboration between flamewing and ColinC10, combining their respective hacks Sonic 2 Heroes and Sonic 1 and 2. It therefore is a single ROM that offers the entire campaigns of Sonic the Hedgehog and Sonic the Hedgehog 2, either alone or together; and enables the player to play as many characters such as Sonic, Tails, and Knuckles. The hack is named due to the ability to control a team of characters, which is reminiscent of the more recent 3D game Sonic Heroes.The hack is built on Sonic 2's engine, which has been enhanced by both flamewing and ColinC10 to have new features. These include: multiple gameplay elements from Sonic 3 & Knuckles, such as element shields and character-specific abilities; the ability to save progress, scores, etc. to SRAM (something rarely implemented in Sonic 2, with the other notable example being Esrael's Sonic 2 Delta); various bug-fixes and improvements to the mechanics of the original games; and many more features, both implemented and planned.

Mobius Evolution is a heavy modification of Sonic the Hedgehog for the Sega Mega Drive created by Abyssal Leopard with the help of fellow members. The aim of this hack was initially to be a simple level layout hack, but it eventually acquired new features, such as innovative gimmicks, boss battles and other things the player might discover in gameplay.

Sonic the Hedgehog Spinball, or Sonic Spinball (ソニック・スピンボール Sonikku Supinbōru?), is a pinball video game in the Sonic the Hedgehog series. It was originally released for the Sega Mega Drive/Genesis in 1993, and later ported to the Sega Game Gear and Sega Master System in 1995.The term "Spinball" is a portmanteau on pinball and "spin dash", a move Sonic performs. It, along with Dr. Robotnik's Mean Bean Machine were the only two Sonic games released to use characters and elements from the Adventures of Sonic the Hedgehog and Sonic the Hedgehog cartoons.