Every race has their version of creation, and some version of The Godswar. No one can prove for certain which is true, but there is a common thread among the myths. The universe was created by a god, who created other gods. Those gods made the stars, and the planets, and all those who dwell within them. Some gods grew unhappy, and decided they wanted to destroy what other gods had created.
The War began. It escalated for millennia, hundreds of gods battling across thousands of light years. Then, in a single massive battle, the gods gathered to decide the war once and for all. No one knows exactly what happened, but the resulting explosion killed most of the surviving gods. The event left a cosmic signature, and is referred to as ‘the big bang’ by the scientists of ancient Terra.
The few gods who survived the big bang became increasingly paranoid. Most hid. Some established empires to worship them.
The galaxy fell to chaos, the children of the gods struggling to establish some sort of order in the wake of massive devastation. They congregated around the bodies of their deities, soon realizing that they could steal power. The first godmarked were born, ripping strength from the minds of their dead parents. Some became demigods, others emperors.
They used the tools of war left behind by the gods to wipe each other out, leading to another round of slaughter. Worlds perished, and several of the remaining gods were killed by the very children they’d once birthed. The few remaining gods wisely hid themselves away, often in treacherous nebulas, or vast stretches of empty space. Some theorize that the beings in the deeps of the Umbral Depths are really surviving gods.
Whatever the truth of things, one thing is undeniable. Dead gods litter the cosmos, and whole nations have been founded around their remains. Mining consortiums exist to cart away bone, or ore soaked in the blood of a god. Such materials have powerful properties, some unique to that patch of asteroids, or to a single world.