@JustLuthor:
Excellent list! There were also some parallel conflicts at the time that had small effects on the war, but I feel are in the spirit of this thread. […] Japan set up a few puppet states in Asia (known as the Greater East Asia Co-Prosperity Sphere) including Manchukuo and Burma, as well as the Philippines, Malaya, Inner Mongolia, and “Free India”, which never held any Indian soil.
Yes, WWII –- and also the years just before it and just after it – was a period which saw many secondary wars and related conflicts. And during WWII, there were large numbers of “bit players” on each side, including a whole bunch of obscure micro-regimes, opposition movements and puppet entities on the Axis side, some of which essentially existed only on paper; one example would be the “Commission gouvernementale de Sigmaringen”, a short-lived Vichy holdover that most people have never even heard of. I’d be inclined to disregard most or all of these micro-entities for A&A gaming purposes, given that even the Global 1940 OOB rules ignore or oversimplify the roles played by much more well-established powers (such as Canada) who made major military contributions over the whole course of the war.
One tricky category are the countries which were genuinely involved in major fighting during WWII, but only for a brief amount of time. Many of these were on the Allied side, such as Poland and Holland and Belgium and France in the first year of the war, and Greece and Yugoslavia in 1941. Iraq is an example on the Axis side. In all cases, they were knocked out in about a month. With the exception of the odd case of France, which actually is a player nation in the OOB rules and actually was a major military and colonial power when the war broke out, I think that most of these intermediate-to-minor nations are ill-suited to being house-ruled as full-scale player powers in Global 1940. I’d likewise discount Allied nations which were in the war only in a marginal role, or entered very late, or both; as I recall, for example, the only Latin American nations which send forces into actual combat were Mexico and Brazil, and even then their contributions were fairly modest.
By contrast, intermediate nations which made a substantial war effort over many years would be potentially suitable candidates for being given a larger role – possibly by being treated as multi-country collective entities, like ANZAC. An example would be to treat Slovakia-Hungary, Romania and Bulgaria as a European Axis Minors block, perhaps with Finland thrown in as well.