My take:
Germany never goes "full retard" with Zimmerman telegram and unrestricted submarine warfare.
U.S., through other technicalities, perhaps sinkings, enters the war 6 months later. Germany gets good forward positions in 1918 and digs in, but cannot knock France out of the war. Germany fights the Allies in a slow retreat to the Rhine. Their navy never mutinies. Germany signs an armistice in the Fall of 1919, the terms are much less harsh but it cedes significant German territory in the west. Germany loses much of its gains from Brest-Livtosk, but retains Danzig and German-speaking areas in modern-day Poland.
The Weimar Republic, in some other form takes shape during the 20s and falls to a military despot in 1934, who models his administration on Mussolini's. He has dreams of a "restored Germania." WIthout the Versailles Treaty, the German military and economy is in a better position. The Germans have a much more impressive, though decrepid, Baltic fleet that is no match for the British but can do just fine against Russia.
Germany prepares for WW2 with a WW1 mindset. They fruitlessly build up their navy, using tons of resources. They take a keen interest in tanks, seeing how successfully that technology pushed them to the Rhine in 1919. They also build up an airforce, who is led by Erhard Milch.
Germany begins by annexing Austria, but cannot annex back German territories in the west without resistance. Germany then moves onto Czechoslovakia, which pretty much starts an arms build-up in Europe.
In 1941, RUssia has begun a war in FInland and in 1942, occupied the Baltic states. The Western Allies have already taken over Narvik, but the Finns have already sued for peace. The USSR and the west are very distrustful of one another. The USSR begins a costly war with Poland.
Feeling contained on all sides, Germany feels that their window of opportunity to act will be lost, so immediately they begin a surprise attack. Though the push back the French and overrun most of Belgium, it becomes a slugging match. THe Germans do adapt, and eventually overrun the French in 1944. THe Italians, at the last moment, do the same. At this time, Stalin has overrun ROmania, putting Germany in a precarious situation when it comes to their fuel situation.
The U.S. defeats Japan by 1945, the Germans attack Russia. Both the Germans and Americans develop atomic weapons by 1946*. Germany uses them to defeat Russia, but being that there is no blitz in this timeline, Great Britain immediately sues for peace.
There is now a new cold war...
nationalistic, but not anti-semitic Germany, would have not scared away EInstein and would have likely built the A-bomb before the United States, or about the same time.