

Sonic & Knuckles, officially released worldwide on October 18, 1994, continues Sonic's adventure after he arrives on Mushroom Hill and up to the final battle against Eggman aboard the Death Egg. The game ends with Sonic preventing Eggman's Death Egg from launching, which causes it to plummet into a volcano cone. When Sonic and Tails arrive to investigate the now seabound landmass, the former is attacked by the island's guardian, Knuckles, whom Eggman has tricked into believing that Sonic and Tails are thieves who are out to steal the Master Emerald. The island is able to fly due to its connection with the Master Emerald, a mystical gem of immeasurable power which Eggman intends to steal in order to fuel his space station. Robotnik) crash lands on the mysterious Floating Island above the sea.

Following the destruction of the Death Egg, Dr. The plot picks up after the Genesis/Mega Drive version of Sonic 2. It was the first Sonic game to offer save files. Knuckles the Echidna, an eventual member of the series' Power Trio, made his debut in this game as an antagonist.

As in Sonic 2, players can control Sonic the Hedgehog, Miles "Tails" Prower, or both. Sonic the Hedgehog 3, originally released on February 2, 1994, note Groundhog Day, so the launch date was naturally referred to as "Hedgehog Day" in Sega's marketing covers Sonic's arrival at the Floating Island and his journey to Launch Base Zone. It was so ambitious that time and hardware constraints forced them to split it into two separate games: Sonic 3 & Knuckles is Sega's third 16-bit entry in the Sonic the Hedgehog series, and the follow-up to the wildly-popular Sonic the Hedgehog 2.
