"Sonic Adventure" is a 1998 platform game developed by Sega for the Dreamcast. It features Sonic the Hedgehog as the main character, who must stop the evil Dr. Eggman from unleashing a powerful creature known as Chaos. Players navigate through various levels, collecting rings and battling enemies. The game introduces multiple playable characters, each with unique abilities, including Tails, Knuckles, and Amy Rose. It combines traditional platforming with 3D gameplay elements, allowing players to explore expansive environments. "Sonic Adventure" was praised for its graphics and gameplay, becoming a defining title for the Sega Dreamcast.