Sonic & Knuckles

Sonic & Knuckles is a 1994 platform game developed by Sega Technical Institute and published by Sega for the Sega Genesis. Players control Sonic the Hedgehog or Knuckles the Echidna in their quests to save Angel Island; Sonic tries to stop Doctor Robotnik from re-launching his orbital weapon, the Death Egg, while Knuckles scuffles with Robotnik's minion, EggRobo. Like previous Sonic games, players traverse side-scrolling levels at high speeds while collecting rings and defeating enemies.

Sega Technical Institute developed Sonic & Knuckles simultaneously alongside its predecessor, Sonic the Hedgehog 3 (1994); they were planned as a single game until time constraints and cartridge costs forced the developers to split it. The Sonic & Knuckles cartridge features an adapter that allows players to connect the Sonic the Hedgehog 3 cartridge, creating a combined game, Sonic 3 & Knuckles. Sonic the Hedgehog 2 (1992) can also be attached, allowing players to control Knuckles in Sonic 2 stages. Attaching the original Sonic the Hedgehog or any other Genesis game released prior to this will unlock the "Blue Sphere" minigame.

Sonic & Knuckles was released for the Sega Genesis on October 18, 1994. It received positive reviews; critics were impressed with the replay value and lock-on technology, despite its similarity to Sonic 3. The games sold a combined four million copies worldwide, placing them among the best-selling Sega Genesis games. They have since been rereleased in various Sega and Sonic compilations.