Sonic Adventure (ソニックアドベンチャー Sonikku Adobenchā) is a video game created by Sonic Team and released on 23 December 1998 in Japan for the Sega Dreamcast and the first main Sonic the Hedgehog game to feature 3D gameplay.
The story follows Sonic, Tails, Knuckles, Amy Rose, newcomers Big the Cat and E-102 Gamma, in their quests to collect the seven Chaos Emeralds and stop series antagonist Dr. Robotnik from unleashing Chaos, an ancient evil. Controlling one of the six characters, with each with their own special abilities, players explore a series of themed levels to progress through the story.
It received a sequel in 2001, Sonic Adventure 2, marking the 10th anniversary of the Sonic the Hedgehog series. In 2003, it received an enhanced port for the Nintendo Gamecube and PC titled Sonic Adventure DX: Director's Cut.