ok OP i know you said you need rest but i went ahead and uploaded a working version with modded campaigns. I tested it on my laptop which never had the game installed and its working as it should.

https://www.mediafire.com/file/xfyjod3imzqtonx/DarkOmen.zip/file

unzip to any path which doesnt contain non latin letters
navigate to subfolder prg_eng
run regsetup.exe. this sets up registries necessary for the game to load, otherwise it won’t find the folder where game is setup and complain.
if you are paranoid change it to txt and see registries it add yourself.
next, and this is important, in same subfolder, set up compatibility of engrel.exe to windows xp sp2. otherwise you will be getting cd check.

after that, run the game via same exe and it should run. once it runs, play around with resolution settings in dgVoodooCpl.exe to set it up to your liking (fullscreen, anti aliasing, stretched or keep ratio, watermark etc)

after that, change graphical settings as picrel for best graphical fidelity

as far as i can tell i cant alt tab without game derping out but battles are fast and brutal anyway as you would know