Created a custom campaign where Allies; UK and France, can decide to remain neutral (and remain at 85% mobilization) to let Germany and the Soviet Union fight it out. If they choose this option; Bulgaria, Hungary, Romania and Yugoslavia experience mobilization events that swing them towards the Axis after Poland surrenders. An Allied decision to remain neutral gives Germany a diplomatic advantage. USA war readiness declines and Soviet war readiness increases. If Germany attacks Denmark, Norway, Luxemburg, the Netherlands or Belgium the British and French enter the war.
First Impressions
The Allied AI chooses to remain neutral ( I set this at 100% for testing; i.e. Declare war on Germany (YES) or Remain Neutral (NO)) and I launched an early German attack on Russia. The AI does a good job of creating a line and avoiding getting units trapped in pockets. Often as I am about to close on a pocket the AI operates units out. Russian AI is good at defense are quickly operates in units when cities are threatened. It does not appear to be offensively minded, most likely because its forces are spread out responding to threats. I focused most of my units in the south and advanced in the north with a small force of 8 units.
I do think that I launched my attack on Russia too soon with too few German units. As the Axis I also choose not to share Poland with Russia.
