As the reviews state, there is no manual. I don't know this game from when it came out and I was intrigued by it's idea and look so I wanted to check it out. However if you have no experience with the game the main menu alone is hard to figure out. Is there any chance that GOG can provide a manual for this game? Or does somebody know an online source for the manual (aside from YouTube tutorials)?

https://archive.org/details/rules-of-engagement-ii-fleet-operations-manual/RulesOfEngagementII-BuilderManual/mode/2up

you can use those until they post them... ^^,

Yes they did. I used to have the box version and there are several manuals and they have many pages.

So the manuals are not part of the GOG games or not?

There's a link to all the manuals in PDF format on the fan site RULESOFENGAGEMENT2 . COM