Sonic & Knuckles plus Sonic the Hedgehog 3 is a platform game released for the Sega Genesis. Continuing the story from Sonic the Hedgehog 2, it follows Sonic as he crash-lands on Angel Island. Players navigate through various zones to collect Chaos Emeralds and confront Dr. Robotnik, who seeks to revive his Death Egg with the help of Knuckles the Echidna.
The game is a sequel to the Sonic the Hedgehog 2 for the same system and follows on directly from the end of the game, in which Sonic defeated his enemy, Dr. Robotnik; crash-landing on a floating island, Sonic encounters new character Knuckles the Echidna, and must once more retrieve the Chaos Emeralds while also working to stop Dr. Robotnik from relaunching his ship, the Death Egg.