I dont know if it has been discussed in this forum already. I didnt found anything about it, so I thought I could post it...
Knowing not much about game engines myself, I stumbled over this interesting one.
For the engine devs of this forum this might be interesting, because this forum has many high talented engine devs.
It is an open source engine with very interesting capabilities.
I looked a bit through their forum and found a lot of "Quake" talk there.
They even have a Quake model converter and other things.
So it should be worth a look (link to homepage can be found here too):
http://www.youtube.com/watch?v=obWkjRIV ... re=related