Xonotic is a fast-paced libre FPS based on the Nexuiz of old.
Make sure to read the guide at https://xonotic.org/guide/ to learn about various gameplay tricks and client optimizations.
On other systems, you have to use the generic GNU/Linux binary-- just
Here's the step-by-step:
$ tar -zxvf lignux.tar.gz
$ cd xonotic/
Now, just run either
./xonotic-linux32, depending on your architecture (64-bit v. 32-bit).
You can use this script to simplify things. :)