I think the 1936 start is very bold, and opens up for some exciting alternative history wars. But in most games, the designer just want to follow the historical correct timeline and to do that he needs to make rules to force the players to follow the historical correct path, and that usually makes this kind of games into scripted games, making the game a reenactment, or simulation of the real war, and not a real game with free opportunities and free decisions. In the real world anything were possible, US even had color coded war plans made between 1920 and 1939, where War plan Orange was war against Japan, and War plan Orange Red was against both Japan and UK, since they were allied at that time, and this plan involved an attack on Canada. I bet we dont see that happen in this HBG Global War game. Neither War plan Green, the war against Mexico. Because of War Plan White, the domestic uprising in homeland US by commies, the War plan Black against Germany was not popular and US backed Hitler with money to make him strong against Stalin. I bet we dont see that in this game, neither.
I think the rules in a game like this need to be streamlined and general. No special rules.
All playing powers, and all neutral minors, must start as neutrals, or else the 1936 start will have no purpose. If the designer want UK, US and USSR to be the Allies, and Japan, Germany and Italy to be the Axis, he should have made the game start in 1942. Because in 1936, both Japan and Italy, and Romania, and Finland, had been allied to UK during WWI, and it was nothing that would suggest any of them would join Germany in 1940. In 1936 Stalin and the commies was the big enemy off the rest of the world. It were more likely that US and UK would make an alliance with Germany against USSR.
But, in 1939, the enemies Hitler and Stalin become allies, against all common sense, and the Western Allies UK and France prepared to attack USSR from Finland. That would have been a game changer as far as WWII is concerned. But it never happened. And we dont want it to happen in this Global War Game neither, so the designer need to make special rules that makes this a scripted game, and boring to play. I actually see no reason to play this game. I can only manage the dice, not the decisions. Then its not a game, but a simulation.
What I suggest.
Dictator players of Germany, Italy, Japan and Russia can do what they want. They are free to attack anyone, or make deals with anyone, at any time. No rules that say that Russia can only attack 3 specific territories in Turn 2, then they must wait until Turn 4 before they can attack again. Russia already attacked Poland, Finland and the Baltic states in early 1939, why wait to 1942 before they are allowed to attack again ? Dont make sense to me. That is a BS rule that make the game a scripted simulation and not a game. The only thing that would prevent Hitler and Stalin from an attack in the real war, were lack of Tanks and Bombers, and a too strong enemy defense position. The military units on the ground told Hitler and Stalin what to do, not some silly rules in a Rulebook.
The democratic players of US, UK, France etc are different from the dictator players, of course. They are not free to attack anyone as long as they are neutral. Only when one of the Dictator players attack a neutral territory, can the democratic neutrals join the war. The only exception is US, who is double neutral because its population comes from all places of the world, and this player need to take considerations to the opinion. Of course, if UK and France dont feel strong enough, they are not forced to declare war against an aggressor. In 1936 the Dictator players had a flying start on the units production and were military stronger than the rest of the neutrals, so the democratic players would have to decide when they were strong enough to declare war. Germany attack Checoslovakia in 1938, do UK and France feel strong enough to declare war on Germany, or do they wait and purchase more units before a war ? A tough decision. Russia attack Finland or Japan before Germany do anything, is it a smart move for UK and France to declare war on Russia, or do they let it pass ? Any neutral player should be free to declare war only when he think it is a good idea. It should not be like, hey Germany attacked Poland, now UK and France must declare war. What if they dont want ? Maybe the UK and French players want Poland to be controlled by Germany, what then ? Make a scripted spesial rule ? Or let the natural mechanic from the real world work ?
Minor neutral should never be pro or anti anyone, they are always true strict neutrals until somebody attack them. If Russia attack part of Finland, like the Vyborg territory, then the rest of Finland are no longer a neutral. They are anti Russia, and join anyone who is willing to fight with them. If UK and France are able to move units into Finland, then Finland join the Allies against Russia. That is of course not very likely to happen, because of the geography. But Germany is in a position to move a unit into no longer neutral Finland, and then Finland and Germany becomes allies. Of course, if Germany move a unit into a neutral Finland, a Finland that has not been attacked by Russia, then that is considered a combat move, and Finland now become anti Germany, and any surviving part of Finland will join the opposite side.
So basically, if a player moves a unit into any neutral territory, either a minor neutral or a playing power neutral, that move is considered to be a combat move. Democratic powers are of course not allowed to do this before they are at war, so no landing of French fighters in UK as long as they are both neutral. And if Germany land troops in North Africa, that is a combat move. Germany land troops in Libya, now Germany is at war against Italy, and Italy join the Allies. Germany land troops in Algerie, now they are at war against France, and UK may join the fight. Easy as that.
Now, the US entry is tricky, I believe that if no US controlled territory or colony were never attacked, US would never go to war. Exception is if you cross the US safety zone that goes across the Atlantic, or you attack any territory in Latin or South America, or you sink a US surface ship by accident, then US is at war.