Open source, and OpenGL powered strategy game 0 A.D has released a new version. Alpha 9 brings a new Roman Republic faction, a new combat system, a new trading system, improved AI and new animations.
If you are a fan of historical RTS's then you definitely should check this out. 0 A.D is free to download for Linux, Mac and Windows from the WildFire Games website
If you are interested in helping out with the project, you can find details on the Get Involved page.