They made The Law: no more planet crackers, no more capital ships, no more machines of war. No more violence, theft, hatred, or rebellion. The people of the stars would no longer live in fear of evil.
And it worked. It worked, because there was only one rule: violate The Law, get thrown into the Void. Spend the rest of your cycles living in the ruins of the ancient battlefield, watched over by the Guardian AI. Fight for whatever measly scraps of tech you can plunder, but never once forget where you are. Always under the bleeding eye of the star called Alpha Prime — the “Dead Star” — the dark giant left at the center of it all.