Gave up on UHexen. Tried UHexen2. Downloaded
https://archive.org/details/hexen-2 which I first tried running with Odin. Didn't work with memory allocation errors.
Compiled all the binaries I could find in
http://github.com/sezero/uhexen2. Really needs better instructions and a batch file or such to compile with OW. Copied all binaries and the included SDL dll to the root of hexen 2 and I get,
H:\tmp\Hexen 2>h2.exe
Hammer of Thyrion, release 1.5.10 (2025-06-20)
running on Hexen2 engine 1.29 (OS/2)
More info / sending bug reports: http://uhexen2.sourceforge.net
basedir is: H:\tmp\Hexen 2
Detected byte order: LE
Found SDL version 1.2.16
Host_Init
Server using protocol 19 (Raven/MP/1.12)
Added packfile H:\tmp\Hexen 2\data1\pak0.pak (696 files, 34289 crc)
Added packfile H:\tmp\Hexen 2\data1\pak1.pak (523 files, 2995 crc)
Playing the registered version.
UDP_Init: WARNING: gethostbyname failed (Unknown host)
UDP, Local address: 192.168.0.105 (lan0)
UDP Initialized
Exe: 09:09:44 Aug 4 2025
32.0 megabyte heap
Console initialized.
No fullscreen video modes available
FATAL ERROR: No fullscreen modes available at this color depth
Promising but obviously doesn't like 32 bit colours. Be interesting to know how it runs on Windows