The Germans are practically and badly overextended. If they have focused on an objective first, like capturing the oil fields at the Caucasus and getting the badly needed oil, the front would have stabilized well and the Germans could dig in and resupply before rushing north. However it would allow the communists to regroup, rearm and fortify Moscow and Stalingrad.
Another, the great Finnish blunder. Despite repeated pleas by Hitler, Mannerheim (or another, I forgot his name) refused to help the German forces besieging Leningrad. If you could push him to at least complete the encirclement, secure Lake Ladoga and preventing Soviet supplies from coming to the city, Leningrad would have felled easily, allowing the Germans to settle in and possibly aid the exhausted Army Group Center.
However, with the Battle of Britain (rather) and the Afrika Corps draining the German resources further, a Nazi win on the grounds of complete conquest in highly untenable. Eliminate these fronts, kick out Britain out of the war (I don't know how will you do that as Churchill is pretty much determined to continue the war) and you could have the badly needed air support in the Eastern Front.
Another, the great Finnish blunder. Despite repeated pleas by Hitler, Mannerheim (or another, I forgot his name) refused to help the German forces besieging Leningrad. If you could push him to at least complete the encirclement, secure Lake Ladoga and preventing Soviet supplies from coming to the city, Leningrad would have felled easily, allowing the Germans to settle in and possibly aid the exhausted Army Group Center.
However, with the Battle of Britain (rather) and the Afrika Corps draining the German resources further, a Nazi win on the grounds of complete conquest in highly untenable. Eliminate these fronts, kick out Britain out of the war (I don't know how will you do that as Churchill is pretty much determined to continue the war) and you could have the badly needed air support in the Eastern Front.