My take on a Central Powers Victory in WWI -
This is a map of the world in mid-1920.
The United States does not enter WWI, due to a combination of Charles Evans Hughes winning the election of 1916 and the German government making a stronger effort to not antagonize the US. The German offensives in 1918 in the west are a little more successful due to a combination of better timing and luck, and the morale of the British and French is lower. The Germans push a wedge between the British and French parts of the front, and France sues for peace in September 1918 as German troops near Paris.
The Treaty of Aachen (1919) is about as harsh to France as OTL treaty of Versailles was to Germany. France cedes a little territory to Germany, but must demilitarize most of the northeastern part of the country, with no military bases or fortifications allowed. France's army is restricted in size, and it must destroy its tanks and aircraft and not build any more. It must also hand over part of its fleet to Germany.
Britain is relatively unscathed due to its command of the seas and the fact that the German military does not want to face the heavy casualties that would be necessary to drive the remaining British army units completely out of France. Britain has to make a few limited colonial concessions and economic reparations.
Belgium remains technically independent, but its government has to sign agreements that bind the country economically to Germany and all but disarm it.
Italy loses a little territory to Austria-Hungary along the border, but the last thing A-H needs is more unwilling subjects, so they don't take much. Like France, Italy is forced to agree to limit the size of its armies and establish a demilitarized zone in the northeastern part of the country closest to the border with Austria-Hungary.
Germany sets up puppet states in Poland, Lithuania, Courland, White Russia, and the Ukraine (the last is under joint German-Austro-Hungarian influence).
Austria-Hungary annexes the northern part of Serbia plus Montenegro, and holds Albania and Romania as essentially puppet states.
Bulgaria takes territory from northern Greece and southern Romania, and takes Macedonia from Serbia.
The Ottoman Empire keeps all of its territories, and the British agree to evacuate their enclaves in Kuwait and Yemen. Without their aid, the Hashemite and other Arab uprisings are defeated, although there is still some unrest in parts of the Hejaz. The Ottomans also take advantage of their victory to establish a sort of "sphere of influence" in western Iran, and support an Azerbaijani state that broke away from Russia. Between the oil fields at Baku, the oil in southwestern Iran, and the as yet undiscovered deposits beneath their own lands, the Ottomans are poised to become a major economic power as demand for oil increases - if they can keep all of this territory and prevent foreign oil companies from getting all of the revenue.
Russia is in a state of civil war. The Bolsheviks have managed to consolidate their power in most of the heartland of old "Muscovite" Russia, but fear of the Germans and Austrians and their satellite states to the west has prevented them from being able to send as many troops to fight the eastern White armies as they did in OTL. As a result, the White army forces under Kolchak still hold most of the land east of the Urals. Bolshevik-supported partisans are active in parts of the German/Austrian dominated Ukraine and in the parts of the territory held by the White armies, but have had less success in the other satellite states. The Germans and Austro-Hungarians are too war-weary to pursue a major campaign against the Bolsheviks, even though the Bolsheviks are supporting partisans in the Ukraine and communist groups within Germany and Austria-Hungary.
Finland broke away from Russia as in OTL. The border with Soviet Russia is similar but not identical to that of OTL.
Much of Central Asia is effectively controlled by various groups of Muslim rebels - this area is shown in white on the map.
Japan is giving "friendly assistance" to Kolchak and his White Army allies. Japanese forces have effectively taken over part of eastern Siberia that is nominally controlled by Kolchak's government. Unlike OTL there are no American or other allied forces to act as a counterweight to their presence. Kolchak and other White Russian leaders completely distrust the Japanese, but have no real choice but to accept their presence and aid.
Armenia and Georgia are independent states that have allied with the Soviets to keep out the Ottomans (the Armenians did this in OTL, too, but in this timeline the Bolsheviks aren't strong enough to absorb Armenia as a Soviet Republic, so it is still an independent state.
Germany regains all of her African colonies, and gets all of the Belgian Congo, plus large parts of France's African colonies, plus a few pieces of Britain's colonies, plus all of the Portuguese colonies in Africa (Portugal suffers badly for joining the Allies when it looked like they were winning in Africa). Germany also gets French Guinea in South America. The US isn't happy about this last one, but they don't have strong grounds to oppose it - the Monroe doctrine doesn't really apply to territories that were already controlled by a European power and are simply changing hands.
Further away, Britain and Japan refuse to return Germany's Pacific island possessions, or the German-controlled portion of New Guinea. Germany does get her Chinese concession in Tsingtao back, but it is so isolated that Japan or Britain or even the Chinese themselves could take it if they wanted.
Britain also retains enough power and influence to refuse to return Egypt to effective Ottoman control - Britain's only concession is to allow Egypt nominal independence, which they did anyway in OTL 1920s.
German leaders considered demaning part or all of French Indochina, but decided that it would be enough effort to absorb all of the new colonies that they were receiving in Africa.
As of mid-1920, the Central powers (especially Germany) have gained a great deal on the map, but they are very war-weary and it will be a huge challenge to try and keep effective control of all of the new colonies and puppet and satellite states. Only time will tell how successful they will be at this task.
