As per a Facebook discussion I've had with some friends, I'm imaging a story setting in which Germany won WWI and from that time worked to build a German Empire that expanded off planet Earth. This would touch off a cold war of sorts in space.
Germany very nearly did win the First World War, not only in 1914 when their initial invasion of France nearly succeeded (brought to a halt by the First Battle of the Marne by reserve French forces advancing unexpectedly, many ferried by taxicab drivers from Paris who volunteered for the task), but also in 1918, after the defeat of Russia led to Germans shipping more troops west to fight the nearly-successful Spring Offensive of 1918. It so happens that the key battle that defeated that massive German offensive was the Second Battle of the Marne, in which US troops played a key role (the US Third Infantry Division that held their ground there is still to this day called, "The Rock of the Marne").
In my story, the Zimmerman telegram that proposed a German alliance with Mexico in the event of a war with the USA, a message that when exposed did much to arouse US sentiment against Germany, is immediately shown to be a fake. So in this alternate history, when the vote for war comes to Congress, it is narrowly defeated. No US troops arrive in France (even though the USA would continue to sell supplies to the Western Allies), so the Germans win the war in the Spring of 1918.
The Treaty of Versailles still happens, but it is France and the UK that pays Germany rather than the other way around. Germany is economically strong, even relatively so in the stock market crash that still happens in 1929. Germany attempts to build an overseas empire to rival that of the UK and France, but finds the best territories have already been taken (to which the British and French and others hang onto tenaciously in opposition to the Germans--the liberation movements that happened in the 1950s-1970s in our world never succeed in this alternate history). When Robert Goddard's rocketry experiments take place in the USA during the 1920s, the German Empire sees a new means of territorial expansion--into outer space. They employ Wernher von Braun (born in Germany in 1912) to create a rocket program focused not on missiles, but on outer space exploration. Early by our world's standards, say in 1952, the Germans put a man in orbit.
A German victory of this sort would create a sort of international cold war in which all other major powers--the USA, Japan, the UK, and perhaps the Soviet Union and France, scramble to catch up with German technological might and try to put their own colonies in space. It is true that such a cold war could have kicked off something like WWII anyway, but for the sake of this story idea, I'm assuming it does not. With no captured German examples to copy off of, other space-faring nations find themselves a decade or more behind the Germans before they found their own space colonies. By then, the Germans would be well-established on the moon, though inevitably other nations would try to build bases there, perhaps on the far side.
I'm offering this story idea to anyone, but I hope to have time to develop it myself one day. In my version, the Great Depression would not be so bad as it was in Germany in our world, but it would still happen. Nationalist parties would still rise up in protest of unemployment and Communist sympathizers. They would never overpower the Kaiser's government, but they would influence it and wind up being incorporated into it. In particular, an Austrian who had served in the German Army, one Corporal Hitler, would find prominence during the Depression, but in this world in Austria rather than in the Germany of our reality. Austria under this Hitler's influence would petition to join Germany, bringing about a major expansion of German-speaking manpower available and bringing also a major influx of strongly racist and nationalist ideas. Jews would be persecuted but not executed en masse. Israel might still have wound up being founded as a homeland for Jews, but it would be a very different Israel...
I'd still have the USA develop the atomic bomb, but later, after the Germans land on the moon (and people realize it is an ideal base from which to attack Earth). They'd share this secret with the British and probably the French. The Germans would eventually build their own, as would the Soviets and Japanese.
My story would have these Earth-based empires jockeying for influence and power and interplanetary bases by the 2014 of this story world. Space expansion would be vastly more extensive than in our reality. But it would be a dangerous world, exploration carried out by atomic-powered and nuclear-armed interplanetary fleets, with most of the rest of the world loosely allied against Germany, no one really certain whose side Japan is on, bitter rivalries showing themselves between the Soviet Union and France and the UK and USA. The Internet would be a limited development at best as these empires focus on the things that matter to them more--secure communications on Earth and interplanetary space vehicles and weapons platforms and maybe even artificial intelligence in the realm of high tech.
With hundreds of interplanetary craft for each empire, each more heavily armed than a ballistic nuclear submarine on Earth, not only would the interplanetary cold war turning hot potentially vaporize every space colony human ingenuity would have managed to build, it would threaten the very existence of life on Earth...