Creative Assembly and Sega are releasing new DLC for Total War: Rome II, with the Pirates & Raiders Culture Pack bringing three new playable factions to the table.
The Ardiaei of Illyria, the Thracian tribes of Tylis, and the Odrysian Kingdom actually get bonuses for being at war (ensuring a contrasting experience to, well, every other faction out there), and come with new units, traits, and tech/religion trees. We're not exactly sure when the new content will come out, but it can be pre-purchased on Steam now, so we can't imagine it'll be long.