500 Days

How different could the world have been, then and now, if lead-ups and events surrounding the Second World War had occurred vastly differently? What if different alliances had been formed through dramatic circumstances and, subsequently, the tyrants had been unable to wield their evil powers?
In the latter half of the 1930s, Russia and Germany are going through the motions of getting on well with each other until a series of "events" occur. A spectacular explosion kills many fascists including Hitler and the Russians decide to seize the moment and invade. Britain and France declare war on Russia and become allied to a Germany under new leadership. There are more shocks when Stalin disappears just when the Russians seem on the brink of success.
Germany, however, has a great deal of support and there are great sea powers, especially Britain, who begin to demonstrate their vast reach. One of the smallest navies in existence also has a big say in subduing a mighty power.