OK, we got two major timeline separations:
September 1938: Neville Chamberlain isnt conned by commie infiltrators and instead stands up to Hitler, never meets privately with him.
Hitler insists on the invasion of Czechoslovakia. The German General staff ousts him in a coup.
Thus, no WWII, right?
Nope. In Dec 1941 Japan still attacks America. Stalin follows by a invasion of Poland.
Interesting alternate War. Allies are Germany, France, UK, USA, Italy, Poland and even Spain help outs. USSR and Japan are by no means allies. USA still sends some aid to European allies, but concentrates on Japan, does not declare vs USSR. UK and USA fight vs Japan. Germany and the UK completely seal off Russia from the sea in the west, but can the allies hold?
Meanwhile Japan is hit by the full force of the USN. By 1944 Japan is sealed off to it’s main islands and is starving, while some forces remain in China.
Or:
May 1942. Hitler dies. No Barbarossa. With Hitler dead, the British people want peace, and with Germany offering to get out of France (well, not A/L of course nor the Maginot line), peace is quickly signed. Germany and USSR split eastern Europe.
USA and UK turn their full attention to Japan.
Question, is Stalin satisfied with half of eastern Europe? Or does he invade German held areas?