Phantasy Star Universe: Ambition of the Illuminus is a standalone expansion to Phantasy Star Universe. It offers more customizable options for the player character, more possibilities for social interaction, e.g. in a casino lobby, more weapons, more combat abilities, more levels and more enemies.

It also features an offline playing mode which continues the story of Phantasy Star Universe. The player needs to stop the secret organization Illuminus which wants to destroy all non-human races. This time he also can create his own character for the offline mode instead of being restricted to a pre-defined one.