That’s generally what war is about, one country(s) wanting to expand and colonize, and other county(s) trying to stop it to protect their own interests. England was a super power at the time, it won multiple wars allowing it to expand the Empire. With expansion comes a strain of resources and uprisings (like that little conflict in the America’s). Although the English were on the winning side of WWII much of the Empire was disassembled afterwords.
The axis partners had spheres of interest prior to the start of WWII. Germany would dominate Europe, Italy the Med region, and Japan would get Asia and the Pacific. If things had continued to go the axis way, those lines very well could have gotten blurred leading to conflicts among the axis. We all know that the Germans were capable of back stabbing their treaty partners.
Yea the Germans were late to the party, but did colonize in the Pacific and Africa prior to WWI. As a result of WW1 they lost those colonies. It is reasonable to believe that had the war progressed in their favor the Germans would want those lost territories back at some point. Would the Japanese just freely relinquish those Pac territories? Maybe some kind of trade off?
I’m no historian, but I don’t think the Japanese had any interest in expanding into Africa during the war(?). That would fall under German/Italian influence where the Euro axis were already fighting. I’m not saying the Japanese didn’t have the means to make landings in Africa, only that it would probably raise red flags to their axis partners if they did. Plus such a landing would have been a major strain on Japanese ambitions and holding they already had in their own back yard. They chose to keep the NAP w/Russia to continue their conquest of Asia and the Pacific (against the wishes of their strongest ally). I don’t think the Japanese would have looked at Africa unless they got the US to sign a treaty giving them complete reign of Asia and the Pac. Then they may have looked towards Africa or the Mid East???
With that said, I like that fact that if the US goes full tilt Europe the game allows you as the Japanese to venture to into Africa, and other European territories. Same for if the Japanese are getting pounded the Germans/Italians can make gains on the Pac side if they want. I wouldn’t like a set of rules that limit you to one map side or the other. Many people already complain about the Acme Chinese wall as it is.
If a house rule limited axis cross overs, or base certain moves on a domino type of effect, I think that you would also have look at putting in some US spending limits per theater as well.