Sonic Adventure: Sonic Adventure DX Upgrade

Doctor Robotnik uncovers records of an entity called Chaos — a creature that once protected both the Chao and the Master Emerald. When an echidna tribe tried to steal the power of the Chaos Emeralds long ago, Chaos transformed into the monstrous Perfect Chaos and wiped them out. The young echidna Tikal sealed Chaos — and herself — inside the Master Emerald to stop the destruction. Thousands of years later, Robotnik releases Chaos from the Emerald and begins feeding it power. Sonic and his friends must stop Eggman and prevent Chaos from reaching its most destructive form.