Megaman Classic. We need a game that'll finally explain how 20XX was plunged into the nightmare that is 21XX.
that was already explained that the start of the X series
What Megaman X game have you played? I played them all religiously, there was no actual explanation of Wily unleashing Zero upon the world and the disappearance of Megaman.
In before "Megaman was rebuilt into X," creators officially disproved this.
There have been theories circulating about the actual "Cataclysm" the event that led to the eventual demise of the original Megaman. The most common one, being that Zero utterly destroyed Mega and the others, but something happened to the Zero unit to cause it to malfunction/shut down. This explains the "Zero Burial Site" which Sigma stumbles upon.
The only explanation we have to the X universe is this:
Dr. Cain had found the Light Capsule containing X. Following the video record Dr. Light left, Cain learned that Light succeeded in creating an AI that would allow a robot to completely emulate a human being, right down to free will. In fears that X would be corrupted to the fallacies of humanity, X was to be sealed for 100 years to perfect the development of his "mind" allowing him to be a good citizen. Cain, however, released the capsule WAY before that 100 years was up.
Using X's spec, Cain created the Reploids, a replicate android based of the X AI. Soon, the world was completely populated with these amazing robots. However, just as humans are able to give into evil tendencies, so to did the Reploids. These rogue, law-breaking Reploids are called "Mavericks."
It was until Megaman X that we find out that Sigma, corrupted with the Wily Virus, rewrote the virus into the Sigma Virus, allowing it to transfer from Reploid to Reploid and trigger the "Maverick Instinct" forcefully. This is when we were introduced to viral induced Mavericks.
That, is the only told history we have between Megaman and Bass (Megaman 8.5) and Megaman X.
But we really do need a Megaman 9 which will, hopefully, close the classic arc and open to the X arc.