[?]APEX HUNGER GAMES[?]
Are you ready?, Let the games begin!

Lore

The scene is set in Arcadia aka Utopia, referencing a place in Greek mythology that is presented as a city where man and nature live in harmony or a natural paradise. This is also symbolic of the "innocence" and current technological capabilities of Arcadia.

This all changes with the arrival of the mysterious 'spheres' in Pride and Fear, which are enigmatic extraterrestrial visitors promising technology so advanced that it was almost magical to the residents of Arcadia. Though the spheres held an imposing presence over Arcadia, their offers were seemingly benevolent, and offered their technology to Arcadia in exchange for an oath to be upheld. However, proud at their newfound power and afraid of the unknown nature of the Spheres, the people of Arcadia did not hold up their side of the bargain and for their arrogance, the Spheres punished them for it. But more importantly, rifts were forming among the people of Arcadia, supercharged by their newfound power. The "demons" could have been part of the Spheres' way of punishing Arcadia, but I think it's more likely that they were created by the people that were now blind with power, forming factions and turning against each other for self-gain only to leave "ghosts" in their wake.