As Germany, the most likely target capital is Moscow but the Soviets can put up an impressive defence simply by stacking around 30 units in Belorussia on their first turn. This requires a three-pronged land attack to overcome:
1. Spend your $12 on three artillery in Finland.
2. On your first turn: Buy eight tanks. Strat bom Leningrad. Capture East
Poland with all infantry/artillery in range. Assemble all tanks within range
in Hungary (they now have two routes to Ukraine). Push all the defence you
can into Romania and Poland. Swap your western tanks and artillery for the
East France infantry and start moving them east. Ship the Denmark infantry
to Finland with your transport and move in two infantry from Norway. Place
your tanks in Berlin. The Soviets may counterattack Romania, at best.
They’ll probably stack an enormous number of units in Belorussia (south of
Moscow) to defend themselves.
3. On your second turn: Buy eight infantry (leaving you $16+ for units
against USA and UK). Strat bomb Leningrad. Attack Ukraine with all East
Poland and Hungary. Attack Baltic States with all Poland and tanks from
Berlin. Attack Karelia with all Finland. Soviets must now a) attack both
Baltics and Ukraine, splitting their forces and succeeding at neither, b)
attack East Poland, leaving Stalingrad vulnerable, c)attack Ukraine, leaving
Leningrad vulnerable, or d) attack nowhere, fortifying Leningrad and
Stalingrad. a), b) and c) are all positive outcomes. Assume the Soviets do
d).
4. On your third turn: Buy eight tanks. Strat bomb Leningrad. All tanks in
Baltic States go to East Poland. Consider attacking Archangel with Karelia
forces to eliminate the Soviet convoy. Move Berlin infantry to Poland and
place tanks in Berlin.
The Leningrad troops will never make it south in time to save Stalingrad, but
assume they try by shifting a large force south to Belorussia. On turn four,
attack Stalingrad anyway (even if Soviets win the counterattack from
Belorussia, their losses will be devestating) and move your sixteen infantry
and tanks into the Baltic States to threaten Leningrad again. The Soviets in
Belorussia are now pinched between two superior German forces, north and
south, with a smaller German force harassing them in the north along the
White Sea.
Remember, you only need to hold Berlin long enough to keep Moscow for one
turn. Landings in Europe by the USA and UK will not likely be serious
threats before turn five or six, and you can easily hold out at least two
turns longer than that, leaving you in the above situation against the
Soviets with as many as four turns in which to conquer Moscow against a
heavily financially wounded Soviet foe, with probably a clear road to the
Middle East through the Caucasus to help your cause.