Changing Soviets to Japanese side doesnt really work with engine limitations.I am working on a different version , here is a rough draft for new idea;
Tripartite Pact rough draft;
In an alternative universe , Germany builds a much better intelligence and spy network compared to what they had.
Learning the real size and capabilities of the Soviet Union early Germans realize they wont be able to achieve their invasion goals and enter negotiations with Japanese.
Germany , Italy and Japan turn Tripartite Defensive pact into full Alliance
Germans agree to delay the invasion of Soviet Union to the Spring of 1943 and focus their attention to Mediteranian/Africa/Middle East and eventually launching invasion of India , Japanese in return agree to join Soviet Union invasion in Spring of 1943
Germans setup a trap for British intelligence by leaking old invasion plans through a double agent.
These plans reach all the way to Stalin , being a paranoid person he is , he believes British are trying to drag Soviets into war by sending him these plans.
Supposed invasion time comes and passes but German division numbers on Soviet Border keeps getting lower as Germany starts a conquest to the South.
Germany invades/convinces Spain, Turkey , Iraq , Iran. By going through these countries they secure Northern Africa , Middle East and due to lack of supplies Gibraltar and Malta. India is open for invasion but Commonwealth saw it coming , they are dug in and ready
This leads Stalin to believe Germany has no interest for invading Soviet Union.
Germany convinces Soviet Union to make a huge trade deal with Japanese if they pay above average market prices , Japanese agree due to Allied blockade. (Monthly Soviet Shipment should arrive in Manchuria untill 3/43)
an event happening in early war leads USA to prepare for war earlier (Due to Major US warship sunk ? USS Ranger decent canditate ) (How early ?) (Earlier , Essex , Fletcher , F6F , Avenger , SB2C , Larger US Garrisons, everything? )
Game design notes ;
Due to engine limitations , Axis cant have off-map base. Workaround ; Add on-map bases named such as: Rome (naval arrival) , Berlin (land and air force arrival) these bases would not be targeted by Allied player with house rule
Maybe place very heavy static flak so if Allied player attacks by "mistake" gets punished
Staging point for Italian navy (Mogadishu) , Germany Army and air force(Quetta)
Axis supply and fuel needs to arrive with monthly supply convoy mechanic , these convoys would stop by (14/05/43 Mediteranian convoy lane opening date)
Capture of Middle East lets Italian navy leave med , add them
Invasion force strength ? 12 German divisions , artillery , hq , garrison force , base forces , flak. Half of it withdraws a month before Soviet invasion ?
German forces should be perma restricted so they do not spawn at Tokyo if they are destroyed
Trade deal with Soviets allow Japan build ? ;
1)Up to 50 extra DD's , Shinano built similiar to Midway , Heavy Bombers ([G5N1 0 Armor , decent payload 1/42 Arv Date] , [G5N2 1 armor , decent payload 3/43 AD], [G8N1 1 armor , good payload 11/44 AD][G8N2 , MXY7 Ohka , 3/45AD]
2)18 I-400 late 1944 ? Specialized float fighter , dive bomber , torpedo bomber to form a submarine carrier force
IJA Divisions equipped by Germany to fight Soviets ? 10+ with TOE changes at 1/43
Possibly tier IX-X ships from Wows for late war
Couple heavy tank battalions for 1943 , maybe panzer division for 1941
Anything arriving at Aden and Abadan before 14/05/43 should start at Capetown
Force Z deployed to Karachi ?
Fortress India , india should be able to hold against both Germans and Japanese for at least a year
Early US preparation = earlier US everything
China starts with more supply and equipment ?
%50 Dud rate for Mk14
US production speed up by 6 months
Scenario will use extended map
Effective front armor + side armor /2 = tank armor value
I dont know how long this one would take , but its a lot of work might take up to a year