After many wars, humankind dispersed into the stars, some more peacefully than others. A few of their groups survived, some more comfortably than others. Eventually they unlocked the deepest secrets of the universe.

Time-travel led to wars unlike any seen before. Entire lineages prevented to undo mild inconveniences. Paradoxes that brought both morality and reality into question. Genocides to assure tyrants that their mistakes simply never occurred.

Eventually entire universes could be created, first simple and random ones initially filled with thermal, electric, and kinetic energy and simple elements, but eventually complex dimensions that were crystaline or mechanical and even galaxy-sized computers in inter-dimensional sub-space.

Once humans were capable of creating super-complex universes that were atom by atom replicas of the machines that gave them birth, they could essentially create infinite numbers of universes expanding eternally in every direction, some filled with life, some with fire, and some with nothingness.

As these humans became immortal gods, able to create new forces, shooting infinitely hot flames that broke their ancient understanding of conventional physics, teleport any distance or even into any realm, and be threatened by nothing except their own kind, they had only their desires and a new plane of science and philosophy to contend with, if they so chose.