Streets of Rage 2, later released in Japan as Bare Knuckle II: The Requiem of the Deadly Battle (ベア・ナックルII 死闘への鎮魂歌 Bea Nakkuru Tsū: Shitō he no Chinkonka?), and in Europe as Streets of Rage II with a Roman numeral, is a side-scrolling beat 'em up video game released by Sega in 1992 for the Mega Drive / Genesis console. The game is also playable in the game Sonic's Ultimate Genesis Collection. It is the second game in the Streets of Rage series, a sequel to Streets of Rage and followed by Streets of Rage 3. The game introduced two new characters: Max Thunder and Eddie "Skate" Hunter (known as Sammy Hunter in Japan), brother of Adam Hunter from the original game.

Streets of Rage 3, known in Japan as Bare Knuckle III (ベア・ナックルIII?) and subtitled Tekken Seiten (鉄拳聖典 lit. Iron Fist Scriptures?) in pre-release media and the official soundtrack release, is a side-scrolling beat 'em up released by Sega in 1994 for the Sega Mega Drive/Genesis. It is the last part of the Streets of Rage series. It was later released for the Japanese version of Sonic Gems Collection for the Nintendo GameCube and PlayStation 2, and for the Wii Virtual Console on September 24, 2007. The game also appeared in Sonic's Ultimate Genesis Collection for Xbox 360 and PlayStation 3. The game had featured several enhancements over Streets of Rage and Streets of Rage 2 such as a more complex plot, multiple endings, longer levels, increased difficulty, more in-depth scenarios (with interactive levels and the return of traps like pits) and faster gameplay (with dash and dodge moves). Weapons could now only be used for a few times before breaking and could now be integrated with unique moves with certain characters, hidden characters were added and a few cutscenes were included to give the story greater depth.

Eggrobo and Mecha Sonic have delivered a chain letter to Knuckles. It contained the following message: "Send this letter to ten friends of yours, otherwise you'll be paralised and won't be able to walk left or right". Since Knuckles doesn't have this much friends, he (in his desire to restore his normal walking abilities) goes on an adventure to kick their robotic butts.

Knuckles in Sonic the Hedgehog is a fan-made ROM of the game Sonic the Hedgehog for the Sega Mega Drive/Genesis, featuring the character Knuckles the Echidna in place of Sonic the Hedgehog, the game's usual protagonist. The history of the game begins with the release of the Mega Drive game Sonic & Knuckles. The unique cartridge featured "Lock-On Technology" and allowed players that also owned the game Sonic the Hedgehog 2 to link the two together and play the game through as Knuckles instead of Sonic. However, partly because of a poorly matching colour palette, no such feature was included in the first Sonic game (instead, attaching Sonic 1 to the Sonic & Knuckles cartridge unlocked the full version of Blue Sphere). In the ROM hacking community, creating a patch that allowed the gamer to play as Knuckles in Sonic the Hedgehog was considered the "Holy Grail of ROM Hacking." On September 1, 2005, Stealth created a hack that allowed a player to do just that. His hack was called Knuckles the Echidna in Sonic the Hedgehog (Knuckles in Sonic 1, or S1K for short) Knuckles in Sonic 1 one gives Knuckles all the moves he has in Sonic and Knuckles, including gliding, wall climbing, and the spin dash. Not only that, Knuckles can transform into his Super form once he obtains all the emeralds (a cheat must first be enabled).

Metal Sonic in Sonic 3 & Knuckles is a hack of Sonic the Hedgehog 3 & Knuckles. It was created by Darkon360/GothicReaper/LoneDevil. Metal Sonic is playable, complete with additional special moves.