Back in November of 2003 I worked on a Quake 2 mod called NightHunters. The source code is avaialable on GitHub along with fixes to allow it to compile on a modern Linux system (gcc version 9.3.0+). Also available in the repository is a pre-built Linux 64bit library file that can be used with Yamagi Quake II. To install, download nh151.zip or nh151.tgz from the Download section of the Night Hunters web site and then extract to your Quake2 folder.
XQF is a game server browser and launcher for Unix/X11 for many popular games such as the Quake series, Unreal Tournament series, Half-Life etc. XQF is a front-end to QStat, a program by Steve Jankowski and uses the GTK+ toolkit. I was a contributor to this project from 2000 to 2003. License: GPL XQF home page GitHub source SourceForge source