After settling in Green Hills, Sonic is eager to prove that he has what it takes to be a true hero. His test comes when Dr. Robotnik returns with a new partner, Knuckles, in search of a mystical emerald that has the power to destroy civilizations. Sonic teams up with his own sidekick, Tails, and together they embark on a globe-trotting journey to find the emerald before it falls into the wrong hands.Sonic the Hedgehog and his friends live on a planet named earth inhabited by anthropomorphic animals like themselves and humans, which is constantly under threat from the evil human scientist Dr. Eggman, who wants to take over with his army of Badniks and establish the Eggman Empire.In search of the missing Chaos emeralds, Sonic becomes stranded on an ancient island teeming with unusual creatures. Battle hordes of powerful enemies as you explore a breathtaking world of action, adventure, and mystery.