The Saraphian War – also called The Great Cataclysm – is the direct result of the Battle of the Cylinder – which itself is also called the 168 Hour War due to the battle stretching for a full week. Inspite of the small, regional-scale conflicts and highly trained units of each and every superpower across Saraphia – primarily the Holy Kalandrik Empire, the United Conglomerate of Imaq, the Gu'Gauv (later the United Kingdom of Orum) and ultimately the Nadiyan Empire – weapons of mass destruction were also being used which resulted in many civilizations within and outside enemy territory being annihilated.
The Kalandriks under James Zavier's rule tried and failed to bring any "alien" races to extinction, due to their superior tactics of guerrilla warfare, revolts, efficiency or a combination of the three. By the end of the war the Kalandriks were the losers only to be forgiven by the Nadiyans and help form the Galactic Coalition.
The war itself lasted for a thousand years starting not long after the botched Battle of the Cylinder – that itself ended the Diamond Age, and ended with the Nadiyan assault on major military and politic targets on Kalandra itself, following the Kalandriks' failed attempt to annex Nadiya. The Kalandriks could've also faced annexation of the Imaqi, but the Nadiyans shot that idea down, not wanting the Conglomerate take more space in Saraphia when they already have enough to rule over.
The Holy Kalandrik Empire is the prime example of ineptitude, over ambition and blind faith ruled over a man and later his apprentice who sought to rule the galaxy in a short span of time – only to take longer than anticipated which led to revolts within Kalandra that grew from a small minority into the majority by the final hours of the war.
But what if that changed?
What if in an alternate timeline: The HKE finally won the Saraphian War?
If the Empire were to win the war, then they would either need to adapt new tactics in order to become at least as powerful as their enemies or – since James Zavier's the personification of Leviathan – unleashed his Goblin Sharks and Vampire Flies to the very capitals of each empire. Goblin Sharks with their Beam Guns disintegrating every soldier, every tactical officer, and every civilian to demand surrender. Meanwhile, Vampire Flies attacking Shuttle Crusiers, destroying Spaceports and Reach Hubs, and even attacking the Jincillans once found.
With every island across Saraphia under Leviathan's grasp, he reveals his true form upon his servants, disciples and loyalist: an alien god banished onto this very island his brother created – out of curiosity. And now with his regained powers and his children as his knights and bishops, he only used the Kalandriks as his scapegoats and pawns, and proceeded to order his children to commit genocide now that their purpose was completed.
Whether or not he'd be using the Kalandriks or his children to finally win the war in a short time as he promised, this was already inevitable from the start. Leviathan, in the end, seeks conquest, what his brother seek curiosity. And now with his regained powers and his children, Leviathan order his Vampire Flies and Goblin Sharks to murder his brother, fully securing control over the very Star Ocean he created and extracting those islands for his eternal life. Afterwards, he could go to another Star Ocean to repeat the process until only he himself remains in The Big Void.
It's surprisingly boring. If evil wins, then he can just jump from one galaxy to another to repeat the process with little resistance. An overpowered god with his children doing all the work for him, since of course he created them while banished on Kalandra by Marduk.
Plus, with Marduk's death before he could choose his champions before they died, that means no KeyMasters, either.