Wow, good topic guys. I love history, especially military history and have done since a very early age. I do love a good "what if" because it really shakes things up and asks us to look at history and significant events in a completely different light.
What if Germany had won WW1?
I think this one all depends on WHEN Germany could have won WW1. If they had managed to capture Paris and score a decisive victory over the British and French in the Summer of 1914 then we would have seen Germany obliviously become the dominant power in Europe and arguably the world. They wanted a maritime empire to rival that of Great Britain as well as be the industrial powerhouse of the European continent.
I think you would have seen her bringing Belgium and Holland into her sphere of influence and cherry picking the best over sea colonies of the UK and France, centred around the lucrative trade routes and countries with rich mineral content.
The question would be, would Russia fight on alone? Remember that the Germans were able to score a huge win at Tannenberg in 1915 and occupy huge swathes of Poland/Russia whilst fighting on the western front too, so a 1v1 situation with Russia would have brought her to the negotiation table sooner rather than later. Again you probably would have seen a similar outcome as the treaty of Brest Litovsk with Germany occupying much of modern day Poland and the Baltic states.
I think you would have seen a swifter decline in the Empires of the UK and France with the indigenous populations striving for independence seeing the humiliating defeat they suffered. Would Germany now continue as a military state or would the people demand democratic reform? There was much calling for more of a shift toward democracy before 1914 in Germany anyway, but I'm not so sure.
Russia would still have had its revolution but the rest of Europe might have been able to intervene more decisively on the side of the White Russians, (especially Germany who would not have wanted an aggressive communist superstate on its border)and we may have seen a democratic Russia form.
Lastly, America might not have become as powerful as it did following WW2 (as this would never have occurred, extreme politics would have stayed on the margins in Germany, if Russia did become communist we might have seen it as the protagonist but that's another story). It might have continued its policy of isolationism although it may have come to blows with a powerful Germany with its new and growing Empire. I don't know enough about economics to say whether the Great Depression would have still have occurred but if id did the powers would have been in a much better state to deal with it (I don't think Germany would have sought reparations because they had scored a quick victory and didn't need to recoup as much or feel as bitter toward the allies).
But for me I think it is/was beneficial for everyone that Germany and her allies had actually won in 1917/1918. She would not have had to loose so much territory and pay so much in reparations thus not allowing extremism to rise so predominately in the post war years. Both her and Austria Hungary would have had to bring in sweeping democratic reforms and again we might have seen a more pro active involvement in helping democracy establish itself in Russia. The world might have been so very different.
PHEW!