Sonic the Hedgehog Plus (often called Sonic 1 Plus) is a hack of Sonic the Hedgehog by Hivebrain. The hack is basically the same as the original game, except with a number of extra features and bugfixes.

Sonic the Hedgehog Thrash is a ROM hack of Sonic the Hedgehog 2 by DalekSam, though it was originally a hack of Sonic 1. It also uses the Sonic 2 Clone Driver.You can also play as Knuckles, credit given to Spanner for the Knuckles object among other things. Honestly, I tried doing it myself but I failed, hard.As of August 2013, the project has since been rebooted from scratch.

Sonic The Hedgehog ZX (also known as Sonic 1 ZX or S1HZX for short) is a hack made by CarrascoZX0 and his team, Team ZX. This hack features the ability to play as Sonic the Hedgehog or Knuckles the Echidna. The hack also features new art, abilities, level layouts, music and much more!

Sonic the Hedgehog Extended Edition is a hack in progress by Cinossu of Sonic the Hedgehog on the Sega Mega Drive/Genesis. In this version of the game, instead of new or fully edited zones, all the original zones are kept intact with minor editing to the acts. Instead, this hack extends the game beyond its original capabilities, including a zone map with warp rings to each act (much like in Sonic Advance 3), saving via SRAM slots (like in Sonic the Hedgehog 3), obtainable upgrades such as the Spin Dash and Super PeelOut (like in the Megaman X series) as well as a new type of ring, emerald, and special stage to add to the mix.While work has not been shown on the hack for a while publicly, a lot of work goes on in private. This is mostly Cinossu either restarting the entire thing from scratch (currently on the 5th restart since conception), or constantly adding and refining new features and ideas. The latest restart is most likely the last one, however, as the disassembly is now so modular that the various chunks can be restarted rather than the entire hack.

Sonic the Hedgehog: Isle of Magnetic Artifacts is a sonic hack made By Neo Team Kyukyokuis a hack which aims to overhaul Sonic 1 using a Japanese-inspired aesthetic. The main feature of this demo is Blossom Gardens Zone, the resting area of the isolated, star-god worshipping Kuratranos tribe. BGZ is a fast-paced experience littered with swift-acting enemies, height-granting gimmicks, driving music, and advanced graphical effects. This new zone can be traversed with three playable characters: Sonic the Hedgehog, Miles "Tails" Prower, and Knuckles the Echidna. Sonic, in particular, features a set of unique sprites, the dropdash ability, and a new companion: Abbey the Flicky. Abbey can pick up nearby rings and circle potential targets for Sonic, including hidden monitors.Neo Team Kyukyoku MembersAngelKOR64: Character programmingChron D: Music arrangementDeltaWooloo: Level layouts, music arrangement, object ports, programming, sound effectsDaxKatter: Music arrangementDio-ZX: Character art, object artDrag109: Level artfuzzy: Level art, programmingiced t: Level art, object artInferno: Level layoutsInktitious: Level artJerry: Level layoutsKatKuriN: Level artKGL: Level layoutsKurk: Team Leader, level layouts, music arrangement, music compositionManiacShard: Object artNaotoNTP: Object artProjectFM: Creative direction, level art, music arrangement, music composition, programming, story planningRaendom: ProgrammingRivet: Programmingtwo^: Concept artyami: Level layouts, music compositionFormer MembersAmzroSevca: Concept art, story planningGemini0: Former team leader, general art, level layouts, programmingjrm1007: Concepts, object artHaz Rabbit: Concept art, programminglavagaming1: ProgrammingNotQuiteHere: Music arrangementpoly: Logo, music arrangementMr. Gandy: Character artXGSOAP: Character artPlaytestersAccelBladeOfChaosCertainly GlitchyCosmic EternityDaxKatterfengishGGK912Hooded EdgeKCEXEKNIJohnMattyMeara BlanchetteMCTravisYTProfessor RendererPXSleekflash-16Sr ParadoxosoapyyTheInvisibleSunUnusualSeekerResourcesAsuharaMoon: Wind-Up Koi spritesAURORA☆FIELDS: SMPS2ASM and AMPSCartoonsAnimate22: Tails and Knuckles spritesCuckyDev: GHZ ball baseflamewing - Ultra DMA Queue + optimized Kosinski (improved by vladikcomper and MarkeyJester) and Enigma decompression codeLone Devil: Metal Sonic spritesMainMemory: SonLVL and Drop Dash programming guideMarkeyJester: DualPCM and sound testMikel Nash: Sonic 3-style super sonic spritesObserver: Sprite ripsShibaMayo: ShibaSaturn spritessnkenjoi: Flex 2The Eighth Bit: Space Queens MIDITheOneMusaab: Sonic 2: The Alternative Spritestildearrow: FurnaceTeck: Super Mario Land - Ending Theme MIDIvladikcomper - optimized Nemesis decompression codeValleyBell: mid2smps, SMPS Converter, SMPS Research PackVladislavSavvateev: DMF2AMPSAssets From:Capcom no Quiz Tonosama no YabouCave StoryFreedom PlanetHigh Seas HavocMega Man SeriesMichael Jackson's MoonwalkerRistarSangokushi Retsuden: Ransei no EiyuutachiShinobi IIISonic SeriesTouhou Project Series

Sonic: South Island Warped is a currently in progress hack of Sonic the Hedgehog. It's main point of interest is the return of the time travel mechanic from Sonic CD, along with a few other new features added to set it apart from the original Sonic 1. Zones are split into four acts each; three main acts and and a boss act at the end. Sonic is capable of traveling to the past or the future of the zone he's currently in via the signposts hidden in each of the levels. Each act, sans act four, has a robot generator that, when destroyed in the past, will remove all badniks for the rest of the act and also create a good future for that act. Destroying all three generators for a zone will remove Eggman's influence in the fourth act, which always takes place in the future.Time Stones also return, collectible alongside the Chaos Emeralds. One Time Stone will be hidden in each zone, and it will only be obtainable within the future of that zone. If attempting to retrieve the Time Stone in the bad future, Sonic will have to face off with one of Eggman's machines. If in the good future, the Time Stone will be unguarded and ready to be collected. The fourth act of a zone contains no generators, Time Stones, or signposts, only a boss fight against either Eggman or Metal Sonic. The Chaos Emeralds will be obtained during these boss fights, usually right after the boss is defeated, but you may also be able to reach it before the boss does, preventing it from making the fight more difficult.As of now, this is just a demo of GHZ, which even on it's own is still in need of much work. Honestly there's a lot I couldn't get around to doing just yet, but I still wanted to give everyone a sample of what I'm making. More than anything, I just hope you all enjoy what you play. Everything in this is release was done by me with the exception of the sound driver and the one original song port done for this hack. Both of those were by Varion Icaria who I can't thank enough for helping out. Also have to give a thanks to the many users of both Sonic Retro and SSRG who made all of the informative guides and tutorials hosted on both sites.