My Oxygen Ran Out, So I Burned the Last Living People on Earth: Antinomia

In a world without oxygen, humanity split in two: those who transformed their bodies to avoid extinction, and those who fled to the sky so they would never forget what it means to be human. Three thousand years later, both factions are right. One needs the last living corner of Earth to survive; the other, to remain human. There are no villains or heroes — only two irreconcilable ways of being right. When the last soldiers of the sky descend to reclaim the planet, they discover that in a world forced to choose between surviving and being human, the most sensible decision is also the most monstrous.