Welcome to Sol, 2400.

The "alt" part of alt-history begins in the 2030s, when world war and nuclear fire scorched the Earth. Such a catastrophic event caused nations to fall, while others rose. As they did, extreme advances in technology and a general will to rebuild and grow pushed humans to the stars, leading them to inhabit every inch of their home system. Even further, human colonies sprouted on neighboring sectors, even where life was not recommended (to say the least). Consequentially, as generations were born on alien planets, nationalities became less important, and the role of states lessened while the United Nations, the only real entity that represented all humans, became more prevalent.

Nations

Most countries, by force or by allyship, banded together following WWIII, forming giganations and huge conglomerates. The USA, Canada and Mexico became the North American Republic, a fervently patriotic if not slightly problematic nation. Europe finally federalized, and not much changed. South America and parts of Africa, tired of the global north's shenanigans, formed the South Hemisphere Coalition, while the Pacific assembled a flimsy union called the Pan-Pacific States, mostly held together by profit and quality of life. The Arab states formed the Arabian League and dedicated themselves to cultural preservation, and the Russian Federation's history ceased with the Second Revolution and the establishment of the communist United Russian Republics. A small number of micronations and governments occupy the system.

The United Nations

After the end of WWIII, in order to prevent another war of that magnitude and to rebuild Earth, the United Nations General Assembly unanimously voted on a resolution to give the UN governmental competences and exclusive powers over certain areas like environment, energy, research, social policy and, most importantly, military strategy for human-wide issues. As nations became less prevalent, the various colonies began to refer more to local UN bases, de facto solidifying its importance and informally assigning it powers it was not intended to have. Nowadays, the United Nations finds itself as the most important entity in the galaxy. Take that, Starfleet.

Gigacorporations

Many companies simply died during WWIII, but those which survived bought or incorporated others until they became colossi large enough to defy governments (and sometimes laws). TriStar Systems is the lead electronics producer, from microchips to computers and more. Hephaestus Industries, a mythos-themed industrial powerhouse, makes ships, stations, and sometimes washing machines. Jincan Pharmaceuticals, possibly just a large mafia officialized into a company, is the largest medicine and insurance provider in the solar system. BFM Banking is a bank that accidentally gained nigh infinite wealth, run by a low profile lawyer from Uganda, which has so far been operating at a total loss but enjoys funding hopeless projects and dreams nonetheless. Galactic Security Solutions is a conglomerate of private military companies, security agencies and private armies at the beck and call of the highest bidder. And Amazon is still here.

Aliens