Publication history of Superman Superman titles have followed two major story arcs. "Action Comics" deals with Superman and wife Lois adopting a Kryptonian child who is revealed to be the child of General Zod. After resolving this arc, Superman has dealt with the return of one of his most dangerous villains, Brainiac which resulted in the arrival of thousands of Kryptonians on Earth and sadly the death of his adoptive father. In "New Krypton", the Kryptonians create a new planet, New Krypton, and raise it opposite Earth's place in the solar system. In "", Superman decides to leave Earth to live among the Kryptonians,
Mongo (fictional planet) the air, which caused acid rain, killed wildlife, and contaminated Mongo's water. The planet became uninhabitable. A small portion of Mongo's people emigrated to Arkaylia. After three generations on the artificial moon, Mongo's environment partially repaired itself. As a result, the people returned to the planet. Clean water, known as "source water", still remained scarce and came from underground. Centuries later, Ming seized power and began his rule. The 1977 Fantasy Games Unlimited role-playing game "Flash Gordon & the Warriors of Mongo" used the planet Mongo as its setting. The game was designed by science fiction writer Lin Carter and