SlackBuildsOrg/games/ioquake3

ioquake3 (An open source Quake 3 distribution)

ioquake3 aims to build upon id Software's Quake 3 source code
release. The source code was released on August 20, 2005 under the
GPL. Since then code has been cleaned up, bugs have been fixed and
features been added. The permanent goal is to create THE open source
Quake 3 distribution upon which people base their games and projects.

NOTE: ioquake3 is just a source code engine port.  You still need the
original game files to play quake3.  For us this means we need one file
from the original CD.  The file you need is [cdrom]/Quake3/baseq3/pak0.pk3
Copy this file to the /usr/share/games/quake3/baseq3 directory.