Ah yes, I’m familiar with “the Stack” approach.
Germany effectively ignores the rest of the game, pulling all units from W and S Europe into the Eastern front. Germany makes no efforts in the Middle East and North Africa. Germany send its wall of Infantry and Artillery forward, and then uses its later Armoured blitzing to catch up to the “Stack” to provide the offensive punch. Russia on the otherhand is typically setup for a defensive fight with lots of Infantry. It’s suicide to send Inf VS Inf without the Armour (and to some extent Artillery) so they can’t counter-attack the invader. As long as Germany can execute its assualt of Moscow on turn 5 or 6 then they have a much higher than 50% chance of victory every time. If that time frame lengthens then the econmic drain from lost territories in W Europe, and N Africa start to shift the advantage back to the Allies and of course every turn Russia has to build up its defense helps Russia.
So here are some changes to try to address the Stack:
1. To collect income from a territory, it must have a unit in it.
This prevents Germany from very-unrealistically pulling every unit on the map into Russia. If they do so, the lost income would greatly reduce the number of tanks Germany can send in later.
This also encourage both sides to fight smaller skirmish battles instead of just have two large stacks, because there is a benefit to clearing a territory even if you cannot take it.
2. All Tank movement is reduced to 1 when within the Russia (Red territories). The Russian territories were vast, and the terrain included vast swamps and marshes. The famed Russian winter also prevented the Germans from making to most of their armour.
This simply slows down the German advance as they penetrate deep into Russian soil. It slows down the reenforcements of those waves of all Armour from reaching the front, affording Russia an extra turn or two. This effect Russia as well, of course, but they start with far less Armour.
Those two I imagine would reduce the Stack success rate without otherwise breaking the balance of the rest of the game too much. Personally, I’d still add on the other options I posted, to enhnace the other theaters of the war, but that’s just me