You can think of this as a crossover of sorts, with elements from Bioshock, Halo, Leviathan and countless other works playing a part. I’ll also have to give special credit to vongrief, Royal Psycho, Ephraim Ben Raphael, Todyo1798 and B_Munro for giving me a lot of inspiration for this scenario.
It is the year 2008 and the world is about to enter what could perhaps be the last war in human history. The last few centuries have been tumultuous ones for mankind. Never before has the human race faced so many threats to its existence. Mankind triumphed, and now it is on equal footing with many of the horrors and abominations it now shares Earth with. But without a threat to galvanize them, humanity has splintered into many different factions, each with its own agenda and each convinced that they, and they alone, should have dominion over the known universe.
The revolutions of 1848 shook Europe to its core, the greatest change to sweep across the continent since the Napoleonic Wars. To the east of the Rhine, the new German Federation arose from the ashes of thirty-eight independent German states. But the Austrian, French and Russian empires endured, forming a strategic alliance to oppose the “radical” states in the rapidly industrializing Germany.
But the revolutions of 1848 were nothing compared to humanity’s first encounter with an extraterrestrial species. The Sarmak, or Martian, Empire was dying as their homeworld slowly became desert. Seeking greener pastures, the sarmaks invaded Earth in the year 1858, along with the various sapient species they had enslaved on their homeworld. For the first time in history, mankind united against this common threat, even halting ongoing conflicts such as the Nanking Rebellion and the American Civil War. The sarmaks succumbed eventually, not to the efforts of mankind but to microscopic bacteria. The sarmaks were forced to abandon their attempt to conquer Earth, and mankind was free to pick over the remains of the Sarmak Empire’s war machine.
The introduction of alien technology sparked a new technological revolution on Earth. Powered by steam and phlogiston, new machines were adopted by mankind in gusto. Clankers, computational machines, made the processing of information extraordinarily easy. Industrial workers were gradually replaced by automated machinery; even the slave systems of Brazil and the Confederate States were gradually abolished in favor of mechanized agriculture. Meanwhile, biotechnology began as its own separate field with the introduction of sarmak technology. Genetically engineered creatures found their way into the military, such as whale-like creatures filled with lighter-than-air gas or mice which can generate powerful electrical charges, but also found use in the civilian sphere. But perhaps the greatest of the new technologies was space travel. Eager to ensure that mankind would not be threatened with extinction, the great powers of Earth moved to Luna and Venus, settling those worlds and subjugating their native populations.
The twentieth century was inaugurated by the Great War, a titanic conflict between the great powers of the Solar System. There were minor conflicts throughout the late 19th century, such as the Sino-Japanese War and the collapse of the Confederate States after its disastrous attempt to take Cuba, these paled in comparison to the conflagration which began with a Serbian revolt in Ottoman Europe. The Russian, Austrian, French and Chinese empires challenged the British, German, Ottoman, Japanese and, later, American empires.
The conflict would rage until 1912, when the American floating fortress-city of Columbia exploded above Peking after a Russian attack, an event now known as the Columbia Incident. Equipped with an experimental teleporter based on ancient Martian technology, the city was intended to launch quick surprise attacks against enemy forces. With the attack over Peking, Columbia’s onboard teleporter exploded, tearing a hole in spacetime. The hole became a gateway for abominations from beyond, both familiar and unfamiliar. Humanity’s old gods, banished from the Earth for reasons unknown, reentered this dimension and waged a war to subjugate humanity once more. Faced with this new foe, the warring powers set aside their differences and focused on fighting the horrors from beyond time and space. The Occult War began.
No victors emerge from the conflict, although humanity did prevent itself from being enslaved. The French, Russian and German governments are overthrown by their people, following radical new ideologies. The French and German governments were overthrown by Rationalists, an ideology espousing focus on the individual and the reduction of government power. Ironically, these Rationalist governments would quickly turn dictatorial in their attempt to assert their power over external and internal enemies. The Russians, on the other hand, embraced Technocracy. Believing human systems to be inefficient, the Russians instead placed their faith in megaclankers, powerful thinking machines. By the 1990s, Russian Technocracy would deem the human form to be too weak, and the Russians seek a way to abandon their flesh and bone for steel and wire.
The British and Portuguese empires fractured under prolonged attack by the Celtic and Norse pantheons. South Africa broke away from British rule and carved out its own empire, controversially reintroducing slavery directed at both humans and aliens. During the global chaos, the Brazilian and Sarmak empires were replaced with communist governments, and the Chinese Empire fractured into many bickering parts. And in the New World, the National Conservative Party took power in Washington and established a one-party dictatorship with ambitions for world domination.
The occult powers, on the other hand, were defeated but not destroyed. The development of atomic weaponry by the human powers forced the gods to the peace table; these weapons could kill gods, but humanity did not have enough to kill all of the gods. The Celtic deities held onto various parts of Britain and France, before exhaustion on both sides forced an uneasy peace. The Norse pantheon was driven away to the far north, while the Olympians were fortunate enough to hold onto parts of Italy. But the Occult War goes on in Egypt, where the forces Akhenaten wage an eternal war against the old Egyptian pantheon and Islamic militants.
The rest of the twentieth century did not see a war as great as the Occult War, but these wars still claimed the lives of millions. In 1941, lizard-esque aliens called the Race invaded Earth, only to be thrown into the Sahara and Arabian deserts after the destruction of their fleet by a combined human-sarmak force. In 1958, an Ottoman megaclanker revolted and founded a “machine empire” in Mesopotamia. Although the Ottomans were able to contain the rebellion, the threat of Russian intervention on behalf of its “machine brother” saved the new Integrated Constructs from destruction. And in 1976, an alien collective known as the Covenant invaded Earth. Having their fleets destroyed by an unknown force, the Covenant were reduced to a small planetoid known as High Charity, and fled to Earth in an attempt to find a refuge from their old foe. Threatened by this presence, humanity made an unholy alliance with both the other sapients of the Sol System and the occult powers to destroy what remained of the Covenant fleet. The city of High Charity crashed into East Africa, where the Covenant were subsequently able to secure some territory for themselves.
By the 21st century, many fear that the final war is approaching. The global system is too unstable to last for long. Humanity is fractured: communists, rationalists, nationalists and conservatives could not stand one another, and each is sure that their ideologies and nations will triumph over all the others. The fanatical red hordes of the Federation of Proletarian Communes thirst for the blood of American soldiers, who likewise wish for nothing more than the destruction of all who oppose the American nation. The unfeeling machine armies of Russia plan on marching through and destroying its friend-turned-enemy, Austria, which has embraced the “illogic” of the preternatural after the Columbia Incident inexplicably gave members of the Habsburg line supernatural powers, but first the abomination known as Chernobog must be made a servant of the megaclankers of Petrograd. The British seek to restore their glory, destroying any who stand in their way.
The non-human threats have also forged their own alliances and have their own designs for world domination. The Misanthropic Understanding seeks to cleanse the planet of the humans and the otherworldy powers which feed off them. The gods seek to expand their power and once more bring the Earth under their rule.
Through valleys and mountains, rivers and oceans, in the skies and in orbit and in the worlds beyond, armies stand at the ready to fight the last war. Only the fear of mutually assured destruction, whether through the atom, the germ, phased plasma or the souls of countless sacrifices, keeps the various powers from starting a war in an instant. But there are countless low-level conflicts and points of contention throughout the Solar System, and if any of these spiral out of control, then who knows what sorts of horrors would be unleashed upon the Earth and the worlds beyond?