Everyone seems to forget the granddaddy of all dystopias[a] on this site, Decades of Darkness. The timeline centers around an alternate *US that adopted a toxic version of Manifest Destiny fused with slavery, after New England splits off from it during the War of 1812. Said *US gradually absorbs a large number of Mexicans, enslaving the mestizos as peons, and continues this way, absorbing all of Central America and South America piecemeal over the course of a century while ethnically cleansing the Caribbean of its Black population. After difficulties with a rebellion in *British Columbia in the 1900s, the *US decides to enslave some of the local white population as "blanks".
Germany experiences much better luck, the HRE managing to resurrect itself as a Greater Germany of sorts including the Low Countries, Czechia and Venice and defeating some of its enemies in the Confederation War. It goes on to weaken France in a sort of *Franco-Prussian war, and gain overseas colonies. In fact, most of Africa is partitioned between Britain and it, with scraps left for France, Greece and others. Only *Liberia in Namibia, populated by freed slaves and people fleeing the Caribbean genocide, along with Ethiopia are left free. Germany ultimately crushes France and England in the Great War of the 1930s, balkanizing them into puppets under military occupation. Afterwards, it gains even more colonies in French *Algeria.
Russia is able to avoid the terms resulting from the Crimean War that prevented it from absorbing *Romania. Despite losing Poland, Russia[c] manages to draw Turkey, Iraq, Syria, Lebanon, Persia, Afghanistan, Xinjiang, Mongolia, Manchuria, Tibet, Bulgaria, North China and Northern Korea[d] into either direct or indirect rule[e] through the weakening of the Qing when the Taiping successfully revolt, and the aforementioned Great War.
Speaking of China, it is divided into two when the Taiping manage to successfully revolt. The Qing become Russian clients, and are occasionally placed under occupation due to revolts. On the other hand, the Taiping gradually collapse into warlordism and are colonized by Nippon[f], Britain, Portugal and Germany, with the interior of South China left to go to hell its own way. This sad state of affairs only ends when Australia occupies S. China during the Great War and lets a free government be created.
By the 1950s, we have a slavocratic *US that stretches from pole to freezing pole, has ambitions of world domination and believes the superiority of the "American Race" over all others, a Germany that uses brute military force to secure half a continent and more, and an expansionist Russia that does the same. The only non-nasty power is the Restored Empire, a gaggle of ex-British ex-colonies that got together after the Fall of England. Bharat [North India] seethes with rage at everyone else, while Africa is mostly under the German and Portuguese boot
[a] Although there is significant disagreement by the author, who claims that Germany and Russia are better than OTL, being federalist democracies and having never experienced Nazism or Stalinism
The original location was even considered by the *US to be too harsh for slaves
[c/e] Russia adopts an odd form of democratic federalism in which vassals/autonomous provinces are basically dominions, although the line between vassals and provinces still has nominal significance
[d] The N. third was captured during a *Russo-Japanese War
[f] Japan's more "nationally correct" name ITTL