ID Software has released the source to Linux doom. Some people are
already porting it:

ftp://ftp.ctr.columbia.edu:/pub/misc/doom/

Get unixdoom.tar.gz. Notice that the guy even did a SunOS/sun3 port.

Hack the Makefile and comment out every .h file that it can't find
while building. I've got it up and running under NetBSD 1.3_BETA.
-- 
Rick Kelly	rmk@rmkhome.com	    rmk@tencats.rmkhome.com
                http://tencats.rmkhome.com
		http://warthog.rmkhome.com