After defeating it temporarily Sonic witnesses Tails crashing in his plane & sets off to rescue him. Knuckles sets off to recover the missing pieces while on Earth in Station Square Sonic does battle with the newly released Chaos who is attacking the police. Dr Robotnik…sorry, I mean Dr Eggman frees Chaos & in the process destroys the Master Emerald which forces Angel Island to crash into the sea below scattering the remaining shards & 7 Chaos Emeralds all over the world. Set on Angel island which floats high above Earth…an ancient being known as Chaos has been trapped inside the Master Island for thousands of years having destroyed Angel Island & most of Knuckles original race. Each’s story is intertwined with each other’s as they attempt to defeat Dr Eggman, an ancient being called Chaos & recover the missing Emeralds. Players get the chance to control not just Sonic but Tails, Knuckles, Amy, Big the Cat & E-102 Gamma (a robot turned good). Sonic Adventure was a hugely anticipated title as it would be the first time Sonic was in a fully 3D title.
After the mistake of not releasing a Sonic game on the Saturn cost the console dearly, SEGA made sure this wouldn’t happen to the Dreamcast by making a Sonic game one of its launch titles.