Hello,
Is there a way to play the game with no opponents? Just for the enjoyment of building?
Basically the craft without the war?

Back in WIn98\Me times we can dublicate network connections and make virual LAN on one PC - without Steam Remote Play Together, without Hamachi and etc. Without second PC.
Probably, this can be done with IPX wrapper bundled with GOG release (or downloaded from ofsite). I dont know how to do it.

www.war2.ru
Ask there. I think it is possible to make a null-bot, but it require some code-working and i dont think someone have enough enthusiasm for that. No good reason. Make bot-allies to skirmish - maybe. but that less possible technically.

Just make map and give opponent (computer) farm without any units, game will finish when u destroy this farm

I swear I recall being able to make opponents that weren't aggressive.

I forgot about it, just set up ai from land_attack to passive