Sonic Adventure brings back the blue blur and his friends to the Sega Dreamcast. The story revolves around Dr. Robotnik's latest scheme to exploit the power of Chaos, a malevolent being that feeds on the power of the Chaos Emeralds . Five heroes will band together to save Station Square and potentially the world.
The gameplay features each character having their own unique take on the platformer genre. Sonic's levels involve racing through a level as quickly as possible, destroying robots along the way. Tails can hover over long distances, and his levels are similar to Sonic's but with an added competitive element. Amy's levels focus on avoiding capture by Dr. Robotnik's robots, using her trusty hammer to break obstacles. E102 Gamma is a slow-moving robot that requires precision and strategy to take down. Big the Cat's levels are more laid-back, focusing on fishing rather than combat.
As players progress through the game, each character can collect items that enhance their abilities, such as rings for Sonic or improved lures for Big. Additionally, the Chao garden allows players to raise and care for baby Chaos , which can be grown stronger by interacting with it in various ways. Completing additional objectives in each level unlocks emblems, but these do not affect gameplay. The game also features downloadable content through SegaNet, although this feature is no longer available due to the shutdown of the service.