The youngest and boldest of all the races, humanity has been through some terrible falls since first venturing to the stars. At first their mission seemed so ambitious, so creative, but this did nothing but anger the Old Gods. Who were these upstarts to think that they could unseat ancient power with new ideas? All of the Old Gods, enemies and allies alike, recognized humans as an existential threat and decided to act. They and their minions descended as one upon the blue-green world of Earth, despoiling its oceans and searing its sky, leaving only a husk that (in time) became the Battleworld where the Old Gods could challenge each other for dominance.
But humans were not done. Pockets of warriors arose from the untouched corners of the planet and the few space colonies that remained. Realizing that they could not hope to militarily remove the Old Gods, they conceived of a strategy to subvert the tournaments and defeat their greatest champions. Humans pretended to acquiesce, in other words, in order to tear down the will of the Old Gods from within.
Many new heroes have joined this effort, martial artists from multiple disciplines looking for a chance to expel Earth's invaders. They bring with them a sense of mission and courage, of mental will and dynamism. Martial artists, combat sports athletes, rebels, soldiers and what is left of the human race represent a new power, determined to throw off the shackles of the Old Gods and reach for the stars anew.