Containing both a single-player RPG campaign and an MMORPG component, Phantasy Star Universe is similar to Sonic Team's previous Phantasy Star Online games, but an entirely new series.

The sci-fi tale takes place in a distant galaxy with several planets. After a mysterious attack, events lead to the discovery of a once-forgotten ancient power, whose possible unveiling leads to conflict. Hack & slash gameplay is the order of the day, while there are also many dungeons to crawl and the usual range of hunting and questing for advancement.

The ability to change classes at will is available without loss of class-specific experience. Online, players can create fully customized characters and fight missions and explore dungeons together.