What is the Storyline of Sonic Unleashed?

Answer 1

In Sonic unleashed what happened was Sonic took in some black mist from the evil creature dark giya that emerged from the Earth which changes him into a werehog at night. Chip or light giya didn't have his memories about sealingdarkgiya because dark giys was meant to come out about a 1000 years later but
Eggman disturbed the balance. Once Sonic had the emeralds back to normal from different giya temples Chip remembers, however the time Chip finds out Dark giya had enough energy to destroy the planet. Sonic is no longer a werehog as the mist emits from his body but with the emeralds he turns super and almost ends it. Sonic's knocked out and Chip summons all the temples to make a guardian and smashes dark giya. Chip and dark giya are once aagaindormant beneath the earth, as Sonic is launched back to the crust's surface with his head stuck in the ground although Chip gave him a bracelet to remember him by. Tails sees him and they go back home.