So, and as said, if that works for you then great. I would be interested in understanding what sort of limitations would apply:
- would you allow an invasion of Spain by either side?
- would you insist on hampering Italy with the Mussolini effect e.g. he must attack Greece or Yugoslavia in 1940?
- would you insist on hampering the UK with the Winnie effect e.g. if Greece goes to war then the British have to intervene with a force (tba)
- do the Japanese have to launch a Pearl Harbor?
- what limitations would you place on the Royal Navy in the Indian Ocean?
- are Japan allowed to attack Ceylon or India or Australia for that matter?
- are the Finns allowed to go beyond their historical 'stop line'
Just some examples as a flavour to help me understand what you mean by realistic. As a keen (very) amateur historian I'd be interested in a game with an AAR.
Spain was courted by both sides, and considered a possible threat by both sides, so yes I think that its feasible, especially if one side is diplomatically enticing them to join the war. So if the Allies see German diplomatic efforts pushing Spain towards war, it is reasonable that they would plan action to preempt such a move, like invading Spain.
The game has an event for Mussolini invading Greece, so I have no problem with it. I also don't have a problem with German troops being brought in through Albania to assist; this is feasible military action, and Hitler did finally assist when he was forced to deal with Yugoslavia. Britain doesn't need to support Greece by landing troops and the game doesn't require it through events or penalties other than landing units does raise their morale. Again, military decision.
Japan did attempt to invade India via Burma, so landing in Ceylon isn't out of the question if the Japanese are doing well. Again, this is within reason as Japan was at war and pursuing just such a strategy; they just weren't successful in reaching India.
Finnish troops were capable of going outside of their country. If Hitler had insisted, and provided significant support, they could've been more active. Once again, failure in taking Leningrad was the major impediment to what the Finns could've done.
Playing strictly by history would be boring. Mainly my "historical" play is about not taking advantage of a flaw in the game to achieve an advantage over your opponent. You aren't "beating" them, your beating the game engine. So military decisions that would be historically feasible are acceptable. Invading Vichy France rather than going through Normandy was considered, and actually done, albeit after the Germans discarded the Vichy government and took control.
What I say to potential opponents is that if you think it might be gamey, it probably is. As I said elsewhere, if they can provide a historical precedence for their action, I'm fine with it. Its about the strategic political/military decisions that are done purely to throw off your opponent, or to manipulate the AI, and are antithetical to one side or the other's historical behavior.