The developers over at Creative Assembly have released their latest patch and content drop, which includes a new playable faction and Steam Workshop support.
The ROME II Workshop
has been up in beta for a couple weeks, allowing the developers to test with some community members to offer original Workshop content from day one. The result is a number of polished unit packs, gameplay modifications, and texture updates to customize your game.
You can read the full details of their announcement and update in the ROME II Community announcements
Total War: ROME II is available here