Sonic 1 - Back to South Island is a Sonic 1 hack made by HyperSonic16.This hack includes new audio, new stage/special stage layouts, new sprites, SPINDASH!!!!!(of course a spindash XD), New level art, and a bunch of badniks(Thanks Robuttnik!) You all are probably expecting a story, so here it is, nice and sweet:Story:Its the Christmas season, and everyone is doing their thing. Tails and knuckles go off to celebrate Christmas on Angel Island. While this happens, Sonic decides to go back to South Island (hence the name of the hack), to celebrate and check up on the flickys. Eggman, strangely had a similar idea, but he plans to robotize the flickys, and rebuild his base. When Sonic arrives, he finds a bunch of badniks, and he immediately knows that Eggman is there. So sonic, being the hero he is, he travels out to stop eggmans plans.

Sonic 1 Beta Remake is a Sonic 1 hack created by Mistergambit, first released on September 14th, 2006. This hack has all of the Sonic 1 levels redesigned to look like their prototype counterparts, as seen in various magazine screen shots. This hack also has new objects, such as a functioning Splats, the checkered ball that was scrapped from GHZ, and more. To make it seem more like a genuine prototype, some levels are made to look unfinished.

Sonic the Hedgehog Brother Trouble is a hack of Sonic the Hedgehog for the Sega Mega Drive featuring Sonic the Hedgehog and Manic the Hedgehog made by MarkeyJester. The hack is notable for its overworld system, new level layouts and graphics and custom boss.

Sonic 1 Color Contrast is a hack of Sonic the Hedgehog for the Sega Mega Drive/Genesis by TheInvisibleSun. It features new palettes and art, modified zone layouts, audio modifications, and various other special additions.

Sonic 1 Dragon Edition is is a modification of Sonic 1 made by DragonWolfLeo that focuses on original art and music to make brand new zones, along with other changes to enhance gameplay.

Sonic 1 Dream Eater is a nighttime hack of Sonic 1 made by Team Overload.In this hack we got 1 stage. Arcana Forest Zone. This hack has no other feature then what Sonic 1 gives you. However if you get all rings you can get to the special stages so you can get the emeralds. While this hack is a demo atm. There will be more progress made when this contest is over.

Sonic 1 Flash Flood is a ROM hack of Sonic the Hedghog that features new palette, audio, zone layout and special stage modifications, in addition to new gameplay mechanics. Flood waters rise and recede at random all over the island, significantly changing how the island is navigated. Can you make it through?Features:Level Design - In addition to the rain effect and water palettes, level layouts are tweaked to account for water physics.Marble Zone has altered lava physics, and Acts 2 and 3 have new shortcuts.Being entirely underground, Labyrinth Zone has been affected a bit...differently by the change in weather.Goggles Monitors - These take the place of air bubbles, and are thus unlimited. Use as many as you need!Badnik Behavior - The rain and flooding is even affecting Eggman's robots and hazards, causing them to malfunction! Some are even enhanced by the chaotic weather. Strangely, most fire-related hazards (such as flamethrowers and fireballs) remain unaffected, defying all logic.Special Stages - New special stage gameplay style, with art and music changes. Get Yellow Rings!Water Physics - Some general quality of life improvements to the water physics, and bug fixes are included here (with a few exceptions, for gameplay reasons).Level Select - Available upon pressing start, no code required. Feel free to check out any zone or special stage at your leisure.Known Bugs:Minor graphical bug in the special stage background, and on the results screen.In the Special Stages, blocks at the edge of the screen being loaded in flicker, due to the amount of objects.Level art mapping glitches crop up on rare occasion.Labyrinth and Scrap Brain's palette cycles are bit buggy at the moment.There are a couple of lingering walk-jump bugs here and therePlanned FeaturesImproved object optimizationImporting Sonic 2-3's child sprite systemUnderwater sound/music modeEven more environmental effects.More significant changes to bosses, Final Boss, etc.

Sonic 1 Lunacy is a work-in-progress hack of Sonic the Hedgehog by the Masochistic Maniacs. The hack features three levels of difficulty (Normal, Hard and Lunatic) with custom levels and ported/custom sounds/music.