It is the year 0099 of the New Century...
At the end of the Common Era mankind had begun to flee its dying cradle on Earth to find a new home in the stars. Instead they found terrible secrets on the moon. Monstrous titans and mysterious crystals. Relics from a long dead empire. This discovery and the cataclysm that would follow would go on to define the rest of human history... We called it The Awakening. An apocalyptic event that shattered Earth's moon and let down a torrent of debris and monstrous lifeforms. The New Century was ushered in by the utter annihilation of human civilization as we know it.
Cities that weren't destroyed by the initial impacts and tidal flooding were greeted by gargantuan frenzied creatures that had fallen among the debris. Wyrms: Ever-growing, ever-evolving, majestic as they are terrifying. From the tiniest mite to city crushing titans, their biology terraformed Earth's barren lands into vast bioluminescent forests teeming with exotic wildlife. These creatures have become a part of daily life in the New Century, as are the colossal and terrible machines we've built to keep them in check...
Today mankind's populations are concentrated in heavily fortified super-cities built to withstand the impending climate apocalypse. No two Bastions were built the same, from the icy citadel of Asgard to deep-sea bio-domes of Ryūgū-jō. From these new city-states an arsenal of super weapons are deployed to brazenly attempt to enforce mankind's dominion over nature... and occasionally each other. In time, a new government formed. For better or worse, the Earth Defense Alliance or EDA became the world's unified ruling body. Governed by the 9 Bastions, the EDA caustically mixes ambition and altruism.
To fuel humanity's engines of war and grand cities, mankind has learned to rely on a new near-limitless energy source; A strange stone that emits incredible thermal and magnetic when near specific individuals: Betyl. Though it still holds a great many secrets, its warm green glow has defined the New Century. Only certain individuals born by pure chance can unlock its incredible potential through Resonance.
It is this power that sits at the hearts of mankinds most powerful and horrific weapon: The Mobile Engagement Chassis. To become a MEC Pilot is to be all at once invincible and expendable. To be blessed with the strength to fight, and doomed to do battle until you fall.
This is your fate... And your choices will go on to shape the future of humanity.