USA does not enter in 1917.
Germany wins in 1918 - but the victory is pyrrhic.
USA does become the major world economic power, and the crash of 1929 has the same effect as IOTL. By this point, Germany's pyrrhic victory has led to much resentment among elites. They begin to eye the rich grasslands of the Ukraine as a possible means to resolve their social and economic crisis. The Russian Tsar, still in command of his throne (I'm assuming it isn't Little Nicky by this point) says "we are one hundred years behind the west, we have ten years to make good the difference or they will crush us". The motto of the 30s is "re-armament for everybody" - regardless of the human cost.
And so, in 1941, everything comes to a head. In the end Berlin is occupied by Britain, France and Russia. Russia itself experiences a centre-left revolution, becoming a social-democratic republic. Britain reorients itself to its empire, as does France (which I suppose would still lose Algeria and Vietnam: the Brits might do better in holding on to their colonies, but there would still be some hard battles to fight there, including literal ones).
Germany, however, shifts, under the bitter weight of defeat, from Kaiserist authoritarianism to full-blown fascism (already in power in southern Europe). And so, in 1968, "they're expecting a third round of trouble", to quote Brecht.