If Germany becomes communist it becomes a military ally of the Soviet Union. Germans will still want revenge for World War I and will reunify by destroying Czechoslovakia, Austria, and Poland. If it's early enough then the communists will give financial support to more communists in the Spanish Civil War and Francisco Franco will not be made leader of the Spanish Empire. There is no Triple Alliance because of the natural opposition between communist and fascism. There probably won't be a major European conflict because Britain and France won't declare war on both Germany and the Soviet Union at the same time. There may be an attempt to assassinate Mussolini and create a communist cou in Rome, which can lead to a war. Imagine potentially a communist Italian and Spanish satellite states in Africa. Japan probably won't attack Allied colonies in the Pacific which will not cause it to invade Indochina nor America to put an oil embargo on Japan. I don't think Stalin would simply invade western Europe. An arms race of sorts might still erupt on the European mainland if the Soviets get the atom bomb in time, which Britain and France may know about and want to use as a deterrent against invasion or nuclear attack.
Japan eventually colonizes all of coastal China until a regional war breaks out. The Soviets will still eventually come to the aid of Chinese and Korean guerrillas against the Japanese occupation which eventually cause it to break down and both nations before the 1980s will be free communist states and the Japanese Empire will cease to exist. Communism will spread much more slowly on a global basis because the last European colonies will probably outlast communism through the 1980s.