Operation Barbarossa: Moscow by Lunch!
Following history, we will go for the knockout punch early and attempt to end the war early by destroying the Red Army (and bagging a few major cities along the way). The real Germans expected things to be done and dusted in eight weeks, but we will take a slightly less naive view and hope to be in Moscow and Leningrad by the end of 1941.
Order of Battle
We have around 4 million personnel at our disposal, arranged into three army groups: North (Ritter von Leeb), Center (Fedor von Bock), and South (Gerd von Rundstedt). More importantly, we are given four panzer groups to work with: Army Groups North and South each get one apiece, with the other two going to Army Group Center.
Scale: 10 miles per hex
As you can see, all three army groups are mostly concentrated along the northern half of the Axis-Soviet Union border. That is because the southern half is mostly mountainous terrain controlled by (Axis allies) Hungary and Romania:
Notice that there is a fourth "army group" under the Romanian Ion Antonescu, which is really just a smattering of Romanian infantry corps which cannot be relied on for much other than rearguard duty. The German 11th Army, deployed just east of the Carpathian Mountains, will help the Romanians out with a push toward Odessa.
As we are pretty much following the historical plan initially, this is roughly what we are trying to reproduce, with September and October being the crucial months that will make or break the campaign:
Plan - Army Group North
The North sector will have Leningrad as the main objective. We are only limited to a single panzer group here and, once we move northeast of the Pskov/Lake Peipus area, will be operating in dense terrain not suitable for mobile warfare. Pskov will also be a midset-shift for us, as we can expect to see Soviet reinforcements showing up in large numbers as we make the outer approaches to Leningrad.
Fourth Panzer Group (Erich Hoepner), which includes Manstein's legendary 56th Panzer Corps, will cross the border and skirt along the northern edges of Kaunas. We force a crossing over the Dvina River near the town of Daugavpils within the first few days, and race to surround Pskov before STAVKA can reinforce it. The ultimate objective will be to reach the southern shore of Lake Ladoga, which will cut off land-based approaches to Leningrad and make the supply situation for the defenders difficult.
We'll also have some help from the extreme north (with restrictions) in the form of our Finnish allies. While the Finns aren't pro-Axis per se, they are no friends to the Soviets and will help us out -- but they are subject to limited rules of engagement. They are free to attack Soviet units anywhere north of the "Finnish No Attack Line" indicated on the map, but cannot do anything south of that unless the Germans manage to occupy Leningrad and link up with them there. The Finns aren't really interested in Soviet conquest, but rather reclamation of territory taken from them in prior conflict.
Plan - Army Group Center
Our strongest army group is given two panzer groups, the 2nd (Heinz Guderian) and 3rd (Hermann Hoth). Having two of these groups gives us a lot of options through the middle, as it were, and we will put them to use like Pacman jaws encircling Soviet armies.
In the north, Hoth will go east toward Vilnius and then wheel southeast to a stop point somewhere east of Minsk. Meanwhile Guderian in the south will bypass Brest-Litovsk on the border, and skirt along the northern edge of the Pripyat marsh on his way to link up with Hoth east of Minsk. A large number of Soviet forces are deployed in this forward salient and we will cut them all off if possible, leaving the infantry armies to close the ring from the west. Once the pocket is sealed, the groups will "open the jaws" again with an eye to creating another encirclement east of Smolensk. It will not be easy going here, as Guderian will have to force his way over the Dnepr River in the face of increasing resistance while Hoth slogs toward Smolensk. Smolensk and Vitebsk anchor a "land bridge" with the Dnepr on the south, and the Dvina in the north and we will have to decide how we want our mobile units to deal with this awkward geography.
Historically the Germans really had no plan for what they would do after Smolensk and neither do we. Depending on the situation, we may either make a push for Moscow before the cold sets in or shift armored units to link up with Army Group South, where the campaign season is slightly longer.
Plan - Army Group South
The going will be slow initially here, where we only have the use of a single slightly-understrength panzer group. The bulk of our units are deployed along a narrow front in between the Carpathians and the Pripyat Marshes, and there will not be much room to operate until we break through into the Ukrainian central plain. The Soviets are also stronger here than in any other sector, with substantial tank forces sitting around.
The initial push will see 11th Army moving north from its jumping-off point in Romania and linking up with von Kleist's panzers. This will be a race to trap most of the Soviet Southwest Front so it cannot fall back and defend Kiev and the Dnepr crossings in numbers. Once we complete this intial encirclement, we will be have wide-open steppe in front of us all the way to Stalingrad. If you look at the difference in terrain between the south and north halves of western Russia, you can see why the Germans never did anything in the Moscow and Leningrad fronts after December 1941 while advancing hundreds of miles all the way to the Volga in late '42. We will likely end up advancing further here than in any other sector, but will have to be careful that we do not outrun our supply lines. We will need to be on solid logistical ground before the mud and subsequent cold sets in.
Supplying the Wehrmacht
Logistics in War in the East, at the core, are not terribly complicated. Both sides have a set of "permanent" supply sources in the form of cities along the west and east edges of the map. Supply is generated in these cities and flows along railroads to the front. Axis formations are organized into the following hierarchy:
Army Group (XXXXX) --> Army (XXXX) --> Corps (XXX) --> Division (XX) --> Regiment (III)
Each of those elements in the chain is represented on-map by HQ units (along with subordinate on-map units in the Army Group, Army, and Corps cases). An HQ unit represents both command/support staff and supply depots/dumps. Divisions are represented as single on-map units but can be further subdivided into regiments as needed, which is particularly useful for armored divisions needing to defend a wide front on the far side of an encirclement. Supply flows down railroads and is then accumulated at HQ units, which distribute them to subordinate units on-demand. The furthermost extent of a rail line is called the "railhead", and supply is distributed from there by trucks taken from a global pool (the "vehicle pool" shown in the top left of the first screenshot). We start the campaign with 176,000 trucks operational for supply distribution. Good roads are hard to come by in the western USSR and our trucks are not generally reliable, so the attrition rate will be high. The goal is to minimize the distance required for overland, truck-based supply distribution. This will not be so much of an issue over open ground in nice weather, but will become an acute concern when mud and snow set in.
Compounding our problems is the difference in rail gauge between Axis and Soviet networks. Because Soviet tracks are spaced wider than Axis ones, rails must be converted by on-map Rollbahn units one hex at a time. Each of these units can convert about 30-40 miles of track per week (one turn) and we only have four of them, so easterly movement of the front will quickly outpace the forward movement of the railheads. We will start to have trouble moving enough gas to mobile units at the front even a few weeks into the campaign.
One weapon in our arsenal that we will use to devastating effect, although sparingly, is the HQ buildup. An HQ executing a buildup expends all its movement points for the turn (i.e. it spends a week sitting idle), but draws extra supply up to 200% of what it normally requires to fully victualize all its subordinates. This allows a panzer corps, for example, to hoard a great deal of supply in advance of a deep penetration during which it expects to be far from any supply source or even temporarily cut off.