Just some background info in case anyone's missed out. Zdoom is a highly customized Doom engine written by Randy Heit and having a GL fork, GZDoom. Enhancements over Doom 2 include immersive cut-scenes, 3D worlds with jumping and swimming, removal of most Doom engine limits, translucency, a powerful Quake inspired console, screenshot tagged game-saves, and support for all Doom engine games including Doom 2, Heretic, Hexen, and Strife.
It does have it's down sides... the worst of which is a very dynamic api where three things come to mind: It uses the closed source (and ever changing) FMOD library for sound and music; Randy occasionally makes disruptive changes of his own; and the GL features of GZDoom mean mods will often only work with either GZDoom or ZDoom. Did i mention Linux support is an f-ing nightmare. See these forums http://forum.zdoom.org/viewtopic.php?f=4&t=10436 ,
http://forum.drdteam.org/viewtopic.php?t=3425 ,
or get some old binaries here http://www.linuxquake.org/index3.html .