When humanity returned to irradiation ridden ruin of Earth they were surprised to see a civilization, of sorts, thriving in the ruins of post atomic desolation. It was always a scientific joke that cockroaches will rule the world after nuclear holocaust and so, the humorous notion became grin reality as the enduring bug evolved rapidly on radiation and seemingly endless supply of food left behind - both in goods and the bodies of the dead. The Megaroaches are already forming primitive cultures. They mastered fire, scavenging and rudimentary toolmaking. If we don’t act now to eradicate them... Who knows when they will have sufficient numbers and smarts to find us and turn on us.