Contraphobe

In the vacuum of space, a silver disk slices the moon, sending fragments into the sun. A fireball hurtles toward Earth, spewing photon plasma into the atmosphere. As the plasma spreads through the ionosphere, it ignites. The people below scream in agony as all life on the surface perishes. Several hundred years later all, as far as the eye could see was desert. Somehow, life exists.
The surface mutants have a tendency to segregate themselves according to their own kind, unless interaction i...