Once unlocked, each character becomes playable with its own storyline, set of moves, and list of objectives. Sonic Adventure DX also lets users unlock the following characters during the course of play: Amy Rose, Knuckles the Echidna, Miles "Tails" Prower, the robot E-102 Gamma, and Big the Cat. The Action Stage requires the "Blue Blur" to complete a specific objective as fast as possible, such as finding his young friend Tails or retrieving one of the game's seven Chaos Emeralds. Once Sonic is ready to embark on an Action Stage, he can leave the Adventure Field at any time to travel to a new destination. Sonic will find himself on a busy street, on a beach resort next to a train station, in a jungle, and various other locales filled with people to talk to and objects to manipulate.
The three Adventure Fields (Station Square, Mystic Ruins, and Egg Carrier) serve as gateways to the game's ten stages. The main aspect of play is the Adventure Mode, which spans multiple levels featuring two areas: the Adventure Field and Action Stage. Players can then transfer the Chao back into the GameCube and raise them however they see fit. Using the color handheld, players will be able to participate in a separate game called "Chao Adventure," which trains the creatures to increase their attributes. This deluxe version of Sonic Adventure features revamped graphics and sound as well as Game Boy Advance connectivity for raising and breeding virtual pets called Chao. Sega's blue mascot makes his third appearance on GameCube as an enhanced remake of 1999's hit launch title for Dreamcast.