Here's the WAD file which illustrates several hard-to-implement and VERY
important WAD features, texture-mapping, difficulty levels, and a couple of
nice features, including monster "turrets," two-part doors, and one-way
wall-doors.  Enjoy, learn, and await the coming of Quake drooling...

Mneumenth, cyborg dragon of Earth and helper of Dominia
mneumenth@kernvalley.com

Oh, yeah, it's MAP01, and won't work in Doom 1.  If there's enough interest,
I'll "port" it to Heretic, Hexus, and Doom 1, as requested and upon availability
of editors for said programs.
