Have the Germans replace Barbarossa for a Southern Strategy with only disabling actions in the North as well as supporting Baltic independence movements. The Germans reach Baku and the Volga by the end of 1941. In 1942 a new northern strategy ends with mixed results, Belarus and much of Western Russia fall into German hands but Leningrad and Moscow survive, albeit barely, with heavy casualties on both sides, meanwhile, the allies successfully land in Africa and soon liberate the continent entirely.
Meanwhile in the Pacific, Japanese forces hit a brick wall in the Phillipines and Singapore, their campaign suffers greatly as a result.
The Soviet Spring offensive of 1942 hits a brick wall against a powerful Volga defence line with heavy casualties. Stalin is running out of manpower and resources and there is still no second front. Without any other option he makes a harsh peace with Germany. Giving up the Ukraine and Belarus in exchange for peace. Although Russia is out of the fight, the Allies are determined to keep fighting and land in Southern France that summer, reaching the Seine by early 1944. Stalin meanwhile, tries to get a consolation prize by invading Manchuria, where a powerful Kwantung Army (Japan has gone on the defensive since it's early setbacks) checks their advance to a degree. To avoid Soviet domination Japan makes peace with the Allies, just around the time that the Red Army reaches the Korean border.
By late 1944, the allies realise that they need a quick way to end the war and thus the atomic bomb is hurried into production, risks are taken and more money is pumped in. However by December 1944 the Americans have one bomb and a target - Berlin.
The Nazi leadership burns and in it's place comes a military junta who unconditionally surrender, unaware that the allies wont have another bomb for several months. They also agree to continue fighting Soviet troops in the Ukraine and Belarus until allied forces can take control there. With the allies settled in, Stalin attempts to attack again, leading an all out allied invasion of Russia. Moscow soon falls, and Russia becomes a pro-western democracy.
How about that?