Blue Sphere is set two years after the events of The Second Story on the planet Edifice, a world currently in a pre-space flight state but holding remnants of an advance civilization. Protagonists from the events of The Second Story are brought down onto the planet by an unknown force, and must work to discover its source and leave. The gameplay carries over multiple Star Ocean elements, including real-time combat and optional side conversations between party members. New elements include item creation tied to the skill system, and local multiplayer options unlock through the Game Link Cable.