Links  
 
 
Our sponsor
  If you're reading me right now is thanks to Echon for keeping the Quake community alive with QuakeDev.com. Pay a visit to the other projects hosted here, all of them are worth a try.
 
QuakeSrc.org
This is the place to go when you think about modified Quake engines. The main source for tutorials teching how to hack the original source, many of the Q2K4 features came from their online tutorials. A must see.
 
Inside3D
  A lot of cool projects and tutorials (mostly but not limited to) in QuakeC. The forums are a good place to check for news in mods.
 
Func_MSGBoard
  The best in Quake mapping happens there. Nuff said.
 
LordHavoc's DarkPlaces
A heavily modified and enhanced engine, DarkPlaces is the source from some features in Q2K4 like colored lights and MD2 support. But it has much more than this. It's worth to check LordHavoc's site in a regular basis.
 
Quake Engine Resources
Although there are no news there for a looong time, the QER page hosts the widely adopted tutorial from Phoenix in animation and movement interpolation, a "must have" to any modified Quake engine.
 
QBism Game Engine
Beginning much in the same way as Q2K4, the QBism project evolved to a heavily modified game engine sporting unique features such MD3 support and shaders.