Sonic 3 & Knuckles: The Challenges is an award-winning hack of Sonic 3 & Knuckles by ColinC10. In this hack the player must complete various levels from S3&K, which newly feature specific challenges to complete, e.g. collecting a certain number of rings or protecting Tails from danger. Completing challenges unlocks more challenges, and players' progress is automatically saved to SRAM.

Sonic 3 and Amy Rose is a fan-made hack of the game Sonic 3 & Knuckles for the Sega Mega Drive/Genesis, with character Amy Rose as playable character in place of Sonic the Hedgehog. The games' sprites (modified from Sonic CD) use Amy's initial design prior to Sonic Adventure. The game was modified by Sonic Retro member E-122-Psi with additional programming and coding by other members including Tiddles, and additional sprite work by ChelseaCatGirl and MotorRoach.

A Hack based on sonic 3 made by Jdpense.The aim of this hack is to be a tag team for Sonic 3 and Knuckles (simliar to the tag team gimmick from Sonic Mania's encore mode), where the player has the ability to swap between two players with the press of a button. Features:- New menu with save feature- Pause menu with minor functions- Tag team gimmick with ablilty to swap partner- Option to change controls for A, B, C buttons- Changed Death functionality- The freedom to explore Sonic's or Knuckles' paths in levels with any character - Player 2 can full have full interaction with the game- New villian character added (Nack the Weasel)

Sonic 3 and Knuckles Time Travel is a Sonic 3 and Knuckles hack made by Jdpense featuring :- New menu screen (WIP) - The ability to time travel like in SCD (ofc)Credits:- Stealth for SonEd2 (newest version)- Xerowhirl for SonMaped- Flamewing for the improved S3k Sound Driver

Sonic 3: D.A. Garden Edition is a hack based on Sonic 3 & Knuckles By D.A. GardenThe project that has been in development since July 2009.the initial idea was to create a ROM hack of Sonic 3 & Knuckles that would provide the player with brand new level layouts from start to finish. In total, 13 Zones of new layouts providing 23 unique acts of game play for 3 characters, and 14 new Special Stages for you to conquer.CreditsMarkeyJester - S3K Layout Padder, SSRG Splash Screen, Invincibility Music Port and Bug FixesUtopiaUK - Testing and Bug FixesMainMemory - Testing and Bug Fixesdjohe - Testing and Bug FixesFlamewing - Bug FixesVarion Icaria - Bug Fixes

Sonic 3C Delta is a hack of Sonic The Hedgehog 3 (& Knuckles). It is a compilation of early/unused content for Sonic The Hedgehog 3, including early music, layouts, graphics, concepts, and more.The hack currently includes all the zones from the first half of Sonic 3, including Flying Battery Zone in its original placement and the 3 Bonus Stages.General Changes:Original zone order.Improved prototype soundtrack.Prototype inspired level layouts.New title screen and menu art.New cutscenes.Prototype graphics and art.Credits:Programming:Chainspike, SyntaxTsundere, Rivet, Inferno, Zummone, Fred Bronze, vladikcomper, lavagaming1Beta Testers:MechaKnuckles, sonic c32ttb1, Xebninmaj Sark, Zummone, Inferno, Volbby, JayKuriN, PhoniexVania, Sprite, EmmaNerd, SyntaxTsundere, Legobouwer9, Rodotnik, Sumi, GigglyManGraphics:Chainspike, MechaKnuckles, Volbby, Trickster, SyntaxTsundere, BladeOfChaos, mcginnis03, Hexagonal, JoeyTheRabbit, EmmaNerdSound:Chainspike, MechaKnuckles, Inferno, Flamewing

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.

Sonic & Knuckles (ソニック&ナックルズ Sonikku to Nakkuruzu?) is a 1994 platform video game in the Sonic the Hedgehog series for the Sega Genesis. It was developed in the United States at Sega Technical Institute by members of Sonic Team, and was published by Sega worldwide on October 18, 1994.In addition to being a standalone game, through a system dubbed "lock-on technology," Sonic & Knuckles acts as an expansion pack to both Sonic the Hedgehog 2 and Sonic the Hedgehog 3, the latter with which it was developed in tandem.