Dr. Light builds Megaman
Dr. Wily builds hundreds upon hundreds of shitty robots, and then builds Gutsman, Zero, Protoman, and Bass
Megaman 1-8 go by. Everyone dies but Zero, Megaman, Wily, and Dr. Light, and Protoman and Bass go somewhere else to fuck with people.
Light builds a NEW HD GRAFIX Megaman, but puts him to sleep for about 20-30 years so diagnostics on his... ability to er, turn evil can be finished. I guess if he was evil, his tube/bed thing would've exploded or something.
Light dies, the original megaman fucks off, and 20-30 years pass.
Megaman X and Zero go and do their stuff for about 500 years.
About as accurate as I remember it from the games.