A free/open source client and automation tool for Ragnarok Online
A MUD client for Android, iOS, Linux, Mac OS X and Windows
KildClient is a powerful MUD client with a built-in Perl interpreter
Major League Baseball Simulation
Retro game engine for creating games like it's 1997
DOOM / Heretic / Hexen source port with enhanced graphics and UI
A nice GUI client for Imperium
A roguelike, contains binaries and source packages for
Free MMORPG
QuakeWorld client ported to OS/2
GGMud is a cross platform modern MUD client.
Moved to http://www.fuzzball.org
Open source server for Other Life/Eternal Lands client
Ground-Up rewrite of MekWars
SkipBo! server and Qt client
Cross platform administration tool for Source Engine dedicated servers
Nexuiz-Xonotic Client