Sonic & Knuckles[a] is a 1994 platform game developed and published by Sega. It is part of the Sonic the Hedgehog series and the sequel to Sonic the Hedgehog 3 (1994). Players control Sonic the Hedgehog and Knuckles the Echidna in their quests to save Angel Island; Sonic tries to prevent Doctor Robotnik from relaunching his orbital weapon, the Death Egg, while Knuckles scuffles with Robotnik’s minion, EggRobo. The game takes place across six levels in which the player collects rings and fights bosses.
Sega Technical Institute developed Sonic & Knuckles simultaneously alongside Sonic 3. The two were intended to be released as a single game, but time constraints and small cartridge sizes forced Sega to split the project in two. The Sonic & Knuckles cartridge features “lock-on technology” that allows the game to connect to the Sonic the Hedgehog 2 or Sonic the Hedgehog 3 cartridges, combining elements from both games. This feature was implemented so the game could be experienced as intended.
Sonic & Knuckles was released for the Sega Genesis on October 18, 1994. It sold 1.24 million copies and received positive reviews; critics were impressed with the replay value and lock-on technology despite its similarity to Sonic 3. Alongside Sonic 3, a Windows port was released through the Sonic & Knuckles Collection (1997). It has also been rereleased through various compilations and on digital platforms such as Xbox Live Arcade and the Wii’s Virtual Console, while it was bundled with Sonic 3 on Steam.
Source