SlackBuildsOrg/games/xonotic

Xonotic is a free (GPL), fast-paced first-person shooter that works
on Windows, OS X and Linux. The project is geared towards providing
addictive arena shooter gameplay which is all spawned and driven by
the community itself. Xonotic is a direct successor of the Nexuiz
project with years of development between them, and it aims to become
the best possible open-source FPS (first-person-shooter) of its kind.

Note: package now includes the dedicated server.

To start a dedicater server:
  - copy doc/server/server.cfg to ~/.xonotic/data/server.cfg
  - edit cfg according to your needs
  - start server via 'xonotic-dedicated'

For server configuration check out the wiki's server section:
https://gitlab.com/xonotic/xonotic/-/wikis/home#server-administration