This is largely inspired by the anime So Ra No Wo To (although I've ignored the world map which implies all the countries are actually located in former Japan), Kornbluth's "Two Dooms" and B Munro's "One Thousandth Anniversary" map scenario. America ended up not getting involved in World War II after Zinegata's bullets hit FDR in 1933 in this world, while Huey Long was not assassinated as America became increasingly polarized under Long's populist and even quasi-fascist Democrats and the conservative isolationist Republicans under Robert Taft. Due to a whole bunch of smart moves, Sea Lion actually happened (ASB I know) and Barbarossa jointly with Japan led to the total conquest of the USSR by 1944. Japan finished conquering coastal China and forced an armistice (with no aid or pressure forthcoming from the US), enabling it to establish a military and economic hegemony over all of East Asia. The Holocaust proceeded apace and soon expanded to include millions of Slavs in Generplan Ost while millions of others were deported to Siberia or "assimilated". A short Cold War between the US and the fascist powers occurred until the outbreak of the Third World War in 1965. Thanks to an Axis first strike, a joint Kriegsmarine-IJN operation succeeded in securing the Panama Canal and Axis troops poured up Latin America from Argentina into the US until all of North America was under the boot by 1972. Two generations of tense Cold War followed between Germany and Japan as they faced each other in Siberia, in Bengal and on the Rockies. In both powers, the government grew immensely powerful and corrupt and ignored the warning signs of resource depletion and global warming
After the attempts of the reformist Fuhrer Heinz Buckliger failed in 2010, he was purged and succeeded by Propaganda Minister Franck Rennicke. The Nazis succeeded in developing a missile defence system and in 2033, on the hundredth anniversary of the establishment of the Reich, Rennicke ordered a massive first strike against Japan, totally annihilating the Home Islands and depopulating much of the rest of East Asia. The missile defence system meant that barely two dozen cities under German or allied control were destroyed although Japanese-engineered plagues killed fifty million before finally being controlled. After the Endkrieg, the few million surviving Japanese (largely those lucky enough to be in the Americas or Australia) were deported to areas where they could be watched more closely and made use of. Many were sent to South Africa or the Congo but about a million was sent to various camps in the Alps in Reich proper and a rump Switzerland (largely consisting of French cantons, the German cantons having voted in a 99% plebiscite to join the Reich in 1976). In an unusually merciful move, Rennicke decided against sterilizing the surviving Japanese. After the established of a true Weltreich and the death of Rennicke (under suspiscious circumstances) in 2055, internal politics reached Byzantine levels of intrigue and disorder while environmental collapse began in earnest. Sea levels rose dozens of feet, desertification occurred in earnest, famines swept most colonial areas, even Germany proper saw severe shortages, and countless species went extinct especially in the polluted oceans. In 2087, the SS joined the banner of revolt under a fanatical SS general and in the war that ensued the few remaining lifelines of oil and other key resources were cut off resulting in a collapse of government throughout the world.
By 2358, 271 years after the Collapse, some semblance of order has returned to the world (now having barely a billion people). Most societies are only at a late 19th Century-early 20th Century levels or at best a World War II level (although certain elements of advanced technology survive such as the huge, walking PzKmpf XIIIs) or are even behind that. The world's major powers are currently Brazil, Argentina, and South Africa. Brazil has the single largest economy in the world heavily based on biofuels. It is relatively wealthy thought not as much per capita as the other Southern Cone countries or South Africa. It is a rather authoritarian republic resembling a Wilhelmine Germany without a monarch. German is widely spoken and enjoys official status along with Portugese having seen several million Germans to immigrate during the Collapse. Brazil has begun harbouring dreams of a truly expanded empire, having established economic dominance over much of the Americas and Africa and even having bases as far away as Lisbon. Brazil's major allies in South America are Venezuela and Chile. Both have large German minorities, and Chile is in addition the wealthiest country in the world per capita. Brazil's main rival in South America is Argentina which is wealthier and prides itself on being more Germanic and "Aryan" than Brazil. It is still under a nominally Peronist regime, but is really freer than Brazil. Its major allies in South America are Peru (Ecuador ended up being annexed by Peru), Paraguay, and Colombia being the product of a Grand anti-Brazilian alliance. Uruguay is quite wealthy and survives as a neutral buffer state between Brazil and Argentina. Across the South Atlantic, South Africa which covers in addition to South Africa proper covers former German Southwest Africa, Rhodesia, and Portuegese Mozambique is the most authoritarian of the major powers, remaining an Afrikanner-dominated regime. Ruthless breeding and establishment of Bantustans means that much of South Africa is now white majority (although they are still only about a quarter of the population), and black majority areas are densely populated and surrounded on all sides. It is the least Germanized of the major powers ironically. North America is a realm of petty states with numerous areas such as much of the Northeast and the Great Lakes still irradiated and uninhabitable. A restored United States of America with a capital at Cincinnati controls little more than the Midwest and the Upper South (and nominally most of the uninhabited areas as far north as the Arctic Circle) which faces off against a black majority Confederate States of America in Montgomery which controls all of the Deep South and extends as far west as Texas. Both are quite primitive compared to the South Americans and the Afrikanners. The USA is a fascist regime with American characteristsics and relatively mild (although virulently racist against blacks) while the CSA is a full-on Nazi state combining the ideas of Marcus Garvey and the Strasser brothers (while the Nazis thought of blacks as little more than subhumans, German-occupied Amerika succeeded in suppressing the KKK and stopping lynchings as the civil rights movement never took off without World War II in TTL). Up north a fascist regime exists in Quebec, and a maritime version of Switzerland known as the Atlantic Confederacy extending over most of the former Canadian Maritime provinces and the northern halve of New England. Its only real purposes is to stay independent from the Quebecois and the Americans and suffers from countless squabbles and disagreements. Most of the Great Plains are under weak states nominally fascist, highly agrarian, and quite poor and the site of rivalry between the former USA and CSA. A few states such as one in former North Dakota still has some bargaining chips thanks to still functioning weapons from over three centuries ago. The West Coast is a collection of feudal states ruled by the few surviving ethnic Japanese over a mixed population of Asians (whites were largely genocided during the Chaos). Mexico is a medium power and a mild dictatorship, increasingly cozying up to Argentina as Brazilian troops have occupied Cuba and built the Nicaragua Canal in response to Colombia's reopening of the Panama Canal. Most of Sub-Saharan Africa outside of South Africa are extraordinarily poor states exploited for resources by major powers although outright colonialism is too much of a burden for the major powers. The major exception is the Swahili Confederacy centred in Kenya which is ruled by descendents of a Wehrmacht division who went "native" and have engaged in some industrialization, managing to keep the South Africans at bay. Two rival "National Socialist" German Reichs exist, the Breslau government controls most of former Poland and eastern Germany as far east as what was once Minsk while the Heidelberg government controls former southern Germany and Bohemia (and nominally most of the still radioactive and depopulated Rhineland). The Breslau regime is far more Nazi ideologically and succeeded in assimilating or annihilating remaining Slav populations in its territory. In addition there is a "Holy Roman Empire" at what was once Innsbruck controlling most of former Austria and northern Italy which is ruled by a monarch who claims to be a descendent of the Wittelsbach Dynasty, the Holy Roman Empire also protects the Pope who is currently at Mantua. In former Switzerland, a hybrid Japanese-French-German society has developed over the ensuing centuries, calling itself the Republic of Helvetia despite being under the rule of a hereditary Archduke. The Helvetians have reclaimed many of the former German cantons and were at war with the "Romans" (as the Wittelsbach Reich is usually referred to as) until quite recently. Their religion is largely Shintoist in beliefs despite having incorporated Catholic architecture and hierarchy and the yen is the currency used. The army uses leftover Wehrmacht uniforms and equipment including a few remaining PzKmpfXIII "Havoks". Most of the Mediterranean lands have undergone desertification and are uninhabited or home to roaming nomadic tribes-this includes the southern half of Italy, Spain, and much of the Balkans. Ireland survived the Collapse fairly well and has now begun the conquest of Great Britain. France is currently divided into the Gallic Republic and Franconia being played off by the Nazi successor states out of fears of a reunited and vengeful France. The Scandinavian Union suffered from nuclear fallout and several very bad winters but now is firmly under the rule of the Swedish monarch and rapidly expanding into the steppes of Russia and raiding the desolate Baltic coast of the Breslau Reich. It is a fairly free and decent state although they do pride themselves as the "true Aryans" rather than the Germans with their Napoleonic Complexes over Aryanism. Former Russia are broken up into several warlord states with a German elite although independent state exist in the Caucauses and Anatolia. The Middle East and North Africa having undergone even worse desertification have only small states at the very edges of the coasts and the river valleys although Egypt is relatively better off after South Africa reopened the Suez Canal. Siberia is home to a fanatical, Holy Slavic Republic which has a maniacal desire for revenge against Germans and Japanese having hardly forgotten the last four centuries of history. The HSR is gingerly grinding the fragmented successor states in European Russia and slaughtering all Germans at sight once conquest occurs. Iran, and the various Central Asian states are all dirt poor and largely ignored by the world after running out of oil. India is utterly balkanized into some thirty different countries and suffering constantly from famine-there are Nazi-inspired "Hindu Nationalist" states, Communist dictatorships, Islamic theocracies, Sikh states, and even a tentative democracy in Maharastah. All of East Asia east of roughly the Yenisey river, and Bengal remain more or less uninhabitable to this day, the product of the Nazi first strike over three centuries ago. A few warlord states exist in the interior of China and Southeast Asia but only at a preindustrial level. The rest of the area has no organization above that of scavenging tribes.
Technology is highly inconsistent even for the major powers. Military vehicles largely run on biofuels or steampower, with many pre-Collapse military equipment have been converted as such. Some areas of North America and Europe have amazingly advanced military equipment around which however is increasingly lacking in spare parts and other replacement equipment and breaking down. Transportation is largely by rail for the major powers although automobiles and ships exist. The major powers use zeppelins and Chile is tentatively testing a Wright-brothers style biplane. Telephones, movies, and radios are quite common in South America and South Africa but rare and used only for the elites or for military purposes elsewhere. Enviromental damage is quite severe-large areas of the world are underwater or desertified and most larger species in the seas have gone extinct. Many scientists strongly fear that this process will continue