Xonotic is a fork of the classic, open-source Nexuiz. If memory serves me, Xonotic was created specifically because of the controversy that resulted from the commercial Nexuiz.

Honestly, I was never too fond of Nexuiz. It always felt kind of floaty to me, and the general sound and graphics design took a backseat for far too long. This new version looks like it very much has consoles in mind. That is never a good sign for anything, let alone a first person shooter.

We shall see, I suppose.