Hi
I believe Proquake also has a linux version (thanks to the mighty Baker), which you should be able to obtain from Quakeone.com (see
http://quakeone.com/proquake/ ) . There
might also be a linux version of the MarkV engine from the homepage (see
http://quakeone.com/markv/) . If you are confortable with making a linux version you could always use the source to the QRack engine (see
http://quakeone.com/qrack/dist/) and compile your own. And finally, you could always try the Linux version of Darkplaces (
https://icculus.org/twilight/darkplaces/download.html) .
Hope this helps
Monty