Amy Rose in Sonic the Hedgehog 2 swaps Sonic out for Amy Rose from Sonic CD, equipped with her Sonic Advance moveset.
She will have to Jump whirl and Dash through Westside Island with the help of her newfound friend Tails!
Infiltrate the Death Egg and put a stop to the deadly Space Station using your hammer!
Super Sonic in Sonic 3D is a hack of Sonic 3D: Flickies' Island made by Sik. This hack allows the player to turn into Super Sonic in said game after collecting all seven Chaos Emeralds, mimicking its prequels Sonic 2, Sonic 3 and Sonic & Knuckles. The rules are borrowed from the latter two games, so the player must double jump to transform and also must not have a shield in that moment, besides the basic requirements (having all emeralds and 50 rings).
All of Super Sonic's behaviour is implemented: a custom palette, a transformation pose with a fading palette, invincibility (with stars), speed shoes and a music change upon transformation. Rings drain while transformed as well. Super Sonic can still be killed by getting crushed by some falling platforms, however, so he isn't completely immune to death.
This hack is based off Sonic 3D: No Flickies, and as such it shares the same gameplay rules.
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.
Sonic 2 XL is a hack of Sonic the Hedgehog 2 for the Sega Mega Drive by Captain Bozo and Ranger. Rings are replaced with onion rings, and Sonic becomes fatter after eating them.
A ROM hack of Sonic the Hedgehog in which the main character replaced by Motobug, one of Dr. Robotnik's Badniks. The new protagonist has a much lower speed, unless when using power-ups.
Amy in Sonic 1 is a modification of Sonic 1 that swaps sonic out with Amy Rose from Sonic CD, bringing with her, her move-set from Sonic Advance.
Using Her Piko Piko Hammer she will have to Jump, whirl, and dash through South Island to put a Stop to Robotnik's plans.
Sonic 2 Retro Remix is a large-scale ROM hack of Sonic the Hedgehog 2 for the Sega Mega Drive, created by Thorn and DNXDelta. The goal of the project is to create a 2D Sonic the Hedgehog game that requires exploration to progress, as well as the requisite platforming and sheer speed. A mission system akin to those of the 3D Super Mario games is implemented as the means of progressing from one level to the next. Missions involve earning Chaos Emeralds in scavenger hunts, boss battles, speed runs and score attacks; most require learning each level's ins and outs, instead of just finding the easiest way to the goal.
Sonic Boom is a total modification of Sonic 2, created by snkenjoi and iojnekns, along with a wide array of talented contributors. As of the Seventh Annual Hacking Contest, this collective is referred to as SÆGA.
Playing as the Pringles mascot, your goal is to reach the finish orb and collect as much Pringles on the way as possible in each level. All levels are split into three worlds, which are based on official Pringles flavors: Sour Cream & Onion, Tomato & Basil and Black Pepper.
Sonic The Hedgehog: The Lost Worlds is a hack of Sonic the Hedgehog 2 by ExecByte. This hack features all of the zones that were cut from Sonic 2 during development. Some zones have been ported from the Sonic 2 Simon Wai prototype and then finished up, and some have been created based on magazine pictures and information from interviews with people who worked on Sonic 2.
Sonic 3D: No Flickies is a hack of Sonic 3D: Flickies' Island made by Sik. The game remains mostly unchanged; however, the Flicky collection system (part of the core gameplay of the original game) has been removed, allowing the player to complete the levels without needing to collect all the flickies in the level to advance. This makes it much more similar to traditional Sonic games, where the goal is to simply make it to the end of the level without dying.
This hack was later built upon further in the hack, Super Sonic in Sonic 3D, which was also created by Sik.