"Beware he who fights monsters, so that he doesn't become one of the monsters himself..."
Earth, at the eve of the 22nd century...
X and Zero, the legendary maverick hunters, had disappeared after succeeding in the hardest mission of their lives, avoiding the collision between Earth and the mammoth space colony Eurasia. They manned to activate the colony's trusters at the last moment possible and instead of the Earth it crashed into the Moon.
Both of the replied as well as their lifelong nemesis, Sigma, were caught on the explosion of the colony and despite all of the rescue teams all that was found of the deceased reploids was Zero's charred saber, which is exposed at the maverick hunter museum under tight vigilance.
For the following years the Earth lived an era of peace, a brief interlude on the war between humans and mavericks. Alas, all dreams must come to an end, and this era's came in the most unexpected way possible.
A transmission came from a mysterious fortress that had been build on the Moon's surface, announcing that the planet Earth were to surrender to the rule of the new leader of the reploid race, our face the consequences.
The man who had claimed this title was none other than, Megaman X.
