Serenity

Nuclear war has been threatened for as long as nuclear weapons have been around. The Cuban Missile Crisis, Chernoybl, those were minor events in history compared to when governments around the world began to do. They started to develop weapons -pistols, shotguns- that would contain nuclear bullets, so that when it would hit it's target, a small nuclear explosion would occur.

They were tested on sick people; men and women who didn't belong in the world. Most of the criminals in the system were wiped out because of the testing. The secrutiy guards and wardens who used to work at the prisons lost their jobs and most starved to death. Others found jobs, but didn't last long because the government wanted to keep it under the radar, but citizens got suspicious when all of the super max prisons shut down. Crime decreased, surprisingly, instead of increasing because everyone learned that if you mess up, you would be killed.

Finally, the United States got everything perfect. They worked out just how much nuclear material you need to put in the bullets for the gun to work properly. They had created the ultimate weapon that the world didn't need. The war was so close to happening then. There wasn't enough room on one planet for all of the hate that was spreading from all the countries.

A solution was found:

Move to another planet.

Our space exploration program improved vastly over the years and we discovered other planets that were deemed livable. Everyone went out to find their own planet to call their own. Everyone deserted Earth because of all it's enviromental problems. But there was still the threat of nuclear war looming right around the corner.