Sally Acorn in Sonic the Hedgehog

Sonic the Hedgehog is a 2D side-scrolling platformer developed by Sonic Team and published by Sega for the Genesis/Mega Drive. Players control Sonic the Hedgehog, who can run at near supersonic speeds and sets out on a quest to defeat Dr. Robotnik, a scientist who has imprisoned animals in robots and seeks the powerful Chaos Emeralds.

A ROM hack for Sonic 3 & Knuckles which swaps Sonic for Sally Acorn (from the Sonic the Hedgehog comics), with her own moveset.

Sally Acorn in Sonic the Hedgehog 2 (aka Sally in Sonic 2) is a fan-made ROM of the game Sonic the Hedgehog 2 for the Sega Mega Drive, with Princess Sally Acorn as a playable character in place of Sonic the Hedgehog.

Sally Acorn in Sonic the Hedgehog (aka Sally in Sonic 1) is a fan-made ROM of the game Sonic the Hedgehog for the Sega Mega Drive, with Princess Sally Acorn as a playable character in place of Sonic the Hedgehog.

What if Sonic Triple Trouble had been originally released on the Sega Genesis / MegaDrive, after Sonic 3 & Knuckles?

A multiplayer-only ROM hack of Sonic the Hedgehog. Two players select a character (one being Sonic and the other being Tails) and both battle it out to try to gain as many hits on Eggman. The catch is that Eggman only gets destroyed when the timer runs down to 0 (unless it's a draw at that time, then, it will wait for another hit). The player with the most hits at the end of the timer wins. The player can also win if the other player dies before the timer runs out (if respawn mode is off).

Batman: The Video Game, is a group of platform games developed by Sunsoft for the Nintendo Entertainment System and Game Boy, loosely based on the 1989 film of the same name. Despite having the same title, each is actually a different game. The NES title is arguably the best known and contains five levels culminating in a final showdown with the Joker in the bell tower of Gotham Cathedral. It was received well despite changes from the movie upon which it was based. Sunsoft later released Batman: Return of the Joker as a follow-up which is not related to any movie.

A Sonic fan game set in the SatAM universe.

A fanmade remake of both Sonic the Hedgehog Chaos and Sonic the Hedgehog Triple Trouble for Sega Game Gear, featuring new characters and habilities, new zones and levels, red star rings to unlock new stages, blue spheres special stages, Time Stones, a 16 bit music mode, a hub world, Ultra transformations, a pause menu, a debug mode and cheats, new color palettes and new player camera, gamepad support, 30 and 60 fps support, 4:3, widescreen and ultrawide.

Sonic Advance Revamped is a remake and slight reimagining of the original Sonic Advance on the GBA, made from the ground up; a passion project designed to be the definitive way to play Sonic Advance! it's a passion project designed to be the definitive way to play Sonic Advance, with better hazard placement, a 16:9 aspect ratio, patched-up levels and bosses, completely redesigned Special Stages, the smoothest sprites from each GBA Sonic title (with some special cases and custom sprites here and there), re-implemented unused/beta elements, and true classic Sonic controls to make the game feel even better.

Sonic the Hedgehog 3D is a free fan game about a famous SEGA mascot, Sonic, and it is made on Build Engine with additional EDuke 32 port. The game was inspired by two classic Sonic series: Mega Drive/Genesis and Sonic Adventure series.

Web browser game based on the special stages of Sonic 3D Blast used for contests on the Sega website.

Sonic Classic 2 is a 2D fangame that is a sequel to Sonic Classic by Hez which will include: Brand New Levels 4 playable characters (Sonic, Tails, Knuckles, and Fang) New unique gimmicks Customizable shields SC1 revamped levels Online Play Extras & More!

Sonic the Hedgehog Classic is a fan game by Hez. It began as an offshoot of his earlier fan game Sonic 1 PC, with a variety of new levels. The game will allow users to play as three characters—Sonic, Tails, and Knuckles—and possibly a custom character of their own. The game features elements from the classic Mega Drive games, as well as new gimmicks. The game currently uses the MMF engine for Windows and has had three releases, with the latest revision (see Downloads) fixing some issues reported by players of the previous version. Moreover, it is Sonic Retro currently being converted to a hack for the Mega Drive by StephenUK. Finally, a few months after releasing the game, Hez Sonic Retro announced that he had started working on its sequel Sonic Classic 2, whose features include various new power-ups and level elements and a complete original soundtrack by Karl Brueggemann.