Sonic Adventure
Sonic Adventure is a 3D platformer video game from the Sonic the Hedgehog series. The player can control six characters from the Sonic universe, each of which has its own gameplay and story angle. The game is divided into two types of levels: Action Stages and Adventure Fields. The division into Action Stages and Adventure Fields is a serious departure from all previous Sonic games. Adventure Fields are non-linear gameplay sections that contain few items and are usually meant for solving puzzles, exploring and advancing the plot. Action Stages are more speed-based and contain rings. Sonic Adventure was the best-selling Dreamcast game and received a sequel in 2001 for the 10th anniversary of the Sonic the Hedgehog series.
Story
Doctor Robotnik is looking for a new way to defeat his longtime nemesis Sonic and conquer the world. In his research, he learns about a being called Chaos who helped protect Chao and the all-powerful Master Emerald thousands of years ago. When a tribe of echidnas tried to steal the power of the Emeralds, breaking the harmony between them and Chao, Chaos used the power of the Emeralds to transform into a monstrous beast, Perfect Chaos, and destroy them. Before it could destroy the world, Tikal, a young echidna who had befriended Chaos, imprisoned it along with herself in the Master Emerald. Eggman releases Chaos and Sonic and his friends must go against Eggman's plans and prevent the monster from becoming even more powerful.