Aqua Magna after Lero's tampering and rearranging.
The Golden Regime Universe is an alternate universe where Matoran Universe was taken over by the being known as Lero Jax.
History
Early differences in the Matoran Universe
The earliest difference from the Core Universe seems to be the existence of one Lero Jax, as records of his life cannot seem to be found anywhere else. Brought into existence at an unknown date and being of an unknown species, Lero was a soldier in the ranks of the League of Six Kingdoms until the banishment of the Barraki. He would go on to become a Mask Maker, learning about the various ways of mask making. After many years of making masks and seeing how various organizations attempted to rule the Matoran Universe made it his dream to create the most powerful mask in the universe. He'd go on to join the Order of Mata Nui in order to gain knowledge of other powerful Kanohi so that his dream could come to fruition.
Point of Divergence
While must history coming from before the establishment of the Golden Regime is either scarce or missing, we do know that Lero eventually succeeded in creating something akin to what could be considered as the most powerful mask in the universe (though most would agree he had two masks; one that contained the most powerful combat related abilities, like speed and strength. And one that contained powers related to space and time) and began his conquest of the Matoran Universe.
The fall of the Order of Mata Nui
Once he created his mask (we believe it to be the combat-related mask cited above), Lero staged a coup d'état. He claimed to be more powerful than Mata Nui himself and after some display of showing off multiple Kanohi abilities at once, gained enough support to march upon the Order's headquarters in Daxia. While the other agents didn't completely believe his bold claim, they still saw him as a threat and sent a taskforce consisting of Brutaka, Jarodin, Botar and several other Toa with the mission of assassinating him. However the mission was a failure as the every member of the taskforce was killed by Lero (it is at this point most historians assume that Lero gained the power of the Kanohi Olmak from Brutaka).
The Siege of Daxia Fortress
After the failed assassination attempt, Lero and his followers besieged the fortress as it was too difficult and risky for an all-out assault (though most historians would agree that Lero fully had the power to destroy the fortress. But he chose to have his followers take part in a siege that would be more rewarding in terms of moral and experience than had he simply demolished it). The siege lasted 276 days until the remaining members launched their final resort in which the Order's Inner circle would escape while the others would make a last stand to buy time. However the escape was intercepted and all of the Inner circle members were killed, most notably Helryx was killed by Trinuma.
Rise of the Regime
Once he had control of the Order, now to be known as Leron Equitum, and access to its extensive data archives, Lero was able to collect the remaining Kanohi or Kanoka he didn't have and set out on his conquest of the Matoran Universe. He started by destroying any organizations that might challenge his rule;
Makuta Extinction
Deeming that the Brotherhood of Makuta and subsequently the entire species, only sought harm on the Matoran, he sent his forces to Destral to wipe out the Brotherhood. The Makuta were caught completely off guard and their headquarters was quickly overrun and Destral was cleared of Matuka. Once done with Destral, the Equitum forces moves rapidly throuugh every island killing the Makuta assigned to the region until none were left. (It should be know that while Destral was attacked, Lero personally sought out Teridax. After learning from his time in the order that he could be dangerous if left unchecked. At this time, Teridax was still a liquid mass of Antidermis sometime after his battle with Takanuva.
TBA (it's late)