Although most cockroaches survived the blasts, their numbers began to dwindle within the first few dozen generations. The buildings, houses, and restaurants that were their preferred habitats had crumbled. Absent a voracious superpredator, both their competitors and the mid-sized animals who preyed upon them flourished. The world would not be inherited by roaches after all.
Instead, rats spread. They too had survived, and they diversified. As centuries spilled into millennia into myriads, the world saw larger rats and smaller rats, sleek swimming rats of the sea, giant trundling spiny rats of the plains, chittering packs of swift, sharp-clawed leaping rats on the hunt, and hairless, upright, tool-wielding cave rats with nimble forepaws and grand designs.
The world became a world of rats, with one rat god to guide them.
Frank Brown Cloud 