On Saturday, June 29, 1901, the Martians launched an invasion of Earth that has since become known as the first War of the Worlds. Though man's most powerful weapons proved useless against the Martians with their mechanical tripods and heat rays, the invaders were brought down by terrestrial bacteria. In the aftermath, the event was fictionalized through a novelization and a disinformation campaign.
The economic depression of the 1970's, with a constantly rising cost of living, marked the rapid deterioration of western civilization. Rather than encouraging the populace to reduce the rapid consumption at the heart of the depression, world leaders opted instead for the rapid proliferation of nuclear fission plants to power more factories to produce more inferior goods from quickly-dwindling natural resources.
Divergence from Earth-616 definitely occurred by the early 1980s. All non-essential funding was shifted to bionics, primarily in an effort to find replacements for limbs destroyed by cancerous sunlight. Farms were moved in-doors, and the use of hydroponics to cultivate food stocks from chemicals began to slowly edge out more natural farming methods. Traditional schooling methods were supplanted in favor of pre-recored, audio-visual lessons undergone at the student's pace in individual cubicles, while teachers did little more than change the tapes. The mural-phonics system, which allowed the audience to see, hear, and even experience the sensations of its subjects through virtual-reality helmets, became the dominant entertainment medium. Militarily, the superpowers continued to research and construct nuclear and biological weapons. A lunar base was established, and at least one mission was successfully landed on Mars. Before the majority of its funding was diverted to bionics research, NASA launched Project Starjump -- an effort to launch a single human, whose life would be prolonged by periodically-interrupted cryogenic suspension, to Beta Centauri IV -- as its last major effort in 1988, with Major Vance Astro as the pilot.
By this time the Bionics Wars -- vast mobilizations of cyborg armies competing for scarce resources and food stocks -- were already raging across the globe. In 1995, a thermonuclear reactor -- one of the many fusion reactors embraced by nations and corporations after 1993, despite popular opposition -- exploded as a result of cyborg fighting. The resulting explosion rendered Western Canada uninhabitable, and worldwide public outcry threatened a massive revolution if the nations could not end the senseless violence. The Bionics Wars formally ended in that same year with the signing of the Treaty of Peking and the formation of the first Confederation of Nations. By the late 1990s, high-speed Transbelt Conveyors became the primary mode of overland shipping and travel. Even more sophisticated artificial reality and sensation systems were developed: Cinderella was re-released in a sensory-stimulating version in 1996, and the octo-tympanum-viewscope -- a fully-immersing system which combined musical tracks with solid-holographic imagery and emotional stimulation -- was developed in 1998.
In 1999, anti-mutant hysteria gripped the world and led to the construction of an army of upgraded, highly powerful Sentinels. The Sentinels decimated the mutant population, killing many in what would become known as the Great Injustice. A band of mutants under Magneto's leadership, known as the X-Iles, abandoned Earth to escape destruction. The group first settled on Jupiter's moon Europa, establishing a city under the northern magnetic pole, but eventually left the Sol system for the planet Haven. Namor conclusively ended the Great Injustice by sending the sentinels to a watery end.
On the night of June 29, 2001, the Martians' launched Attack II, the second attempt to invade the Earth. The Martians' initial assault simultaneously destroyed all human stockpiles of nuclear arms, assuring that not one nuclear weapon would be fired in the course of the war. By morning the Martians had begun dismantling transportation systems. Terran forces used biological weapons against the invaders, only to discover that they had developed a general-purpose immunity. While the Martians sought to keep as many humans alive as possible for food, labor, and entertainment, the biological weapons deployed during the assault killed or mutated many. Armies conducted counter-attacks, and civilians either rose in defense or fled. The second assault -- skirmishes with pockets of resistance, civilian freedom fighters, and remaining superheroes such as Captain America and Spider-Man -- lasted into 2006, but the initial assault had been so devastating that the event soon became known as the One Night War.
Led by a powerful High Overlord, the Martian Masters enslaved most of the population, as labor in converting Terran edifices to new uses, guards for their fortresses, or even as simple cattle. Some were drafted as gladiators to fight for the Martian Masters' amusement, while others were trained as Exterminators to hunt down the last freemen threatening Martian rule. The Martians were particularly interesting in co-opting scientists, many of whom became Keepers, collaborators responsible for overseeing their fellow humans. In 2014, the gladiator Killraven escaped from captivity, and soon became the leader of a particularly troublesome band of freemen. Despite any hopes humanity held for a savior, the Martian force would not depart until 2075, having finally depleted Earth's resources.
With the Martians gone, humanity was free, but barbarous. Societies soon formed around independent city states ruled by techno-barons, who controlled the fruits of scientific progress. In 2188, one such techno-baron named Isaac Harkov developed a theoretical means of faster-than-light travel. For the most part, though, the techno-barons fought among themselves for territory and other prizes. At some point, the serfs rebelled against the techno-barons, refusing to fight for possession of the Moon. By 2525 Kwaal, the last of the techno-barons, was killed by the serfs.
In 2850, Harkov's texts resurfaced, and in 2900, the fuel necessary to implement Harkov's theory of faster-than-light travel was found in quantity at Mercury's core, and dubbed "harkovium". By this time humanity had spread to several planets within the Sol system, using genetic engineering to modify humans to survive in the harsh environments of Mercury, Jupiter, and Pluto. Humans engineered to withstand extreme heat and light operated the mining colony on Mercury. Massive, dense humans were engineered to survive Jovian gravity. Humans were altered into a crystalline, silicon-based form to survive on the manufacturing colony of Mercury. Uninhabitable Venus became home to thermo-electric planets which transmitted power to Earth and its lunar colony via laser relays. In 2908, the first Harkovian starship, Andromeda, was constructed, but lost on its maiden voyage. In 2940 a fleet was launched for Alpha Centauri trinary star system. There humans established their first friendly contact with an alien race: blue-skinned, pre-industrial beings on the planet Centauri IV, a planet orbiting the Beta Centauri star. In 3000, Earth, its colonies, and Centauri IV joined as equals under the United Federation of Earth. In 3006, Vance Astro's ship (all attempts to reach him before this point having failed) finally reached the Alpha Centauri system, where he was dismayed to learn faster-than-light travel had rendered his mission pointless.
In 3007, the peace was shattered by the invading Brotherhood of Badoon. The Badoon would come to completely destroy the human colonies, killing all. On the final push for Earth, the Badoon easily overwhelmed the inferior fleet of the United Lands of Earth, and killed and enslaved millions as the conquered the planet. Guided by the unseen hand of Starhawk, a sole survivor from each colony, along with Vance Astro, sole survivor of the twentieth century, banded together to resist the Badoon as the Guardians of the Galaxy. Eventually, the Sisterhood of Badoon travelled to Earth to take the males into custody. With the Badoon gone, the Guardians found that Earth offered little for them, and re-dedicated the group as an interstellar enterprise, primarily funded by the sale of historical docu-chips Vance made of the group's time-travelling encounters with with being from Age of Heroes, such as the Avengers. Among their many adventures was the "Shield Quest", in which the team (at Vance's urging) followed rumor, myth, and legend to ultimately find the long-lost shield of Captain America.