I have tons of super vivid dreams. One i had recently (i'll keep it short....ish):
Earth's atmosphere has been damaged, and some it's habitability hindered. Mankind makes this artificial moon that orbits the earth. Resources are mined from the arth still. Time passes to the point where life on the actual planet seems like ancient history.
The artificial moon's government has become totalitarian, and has told everyone the earth is inhabitable. Everything and everyone is tracked, connected, and managed. Call it a smart moon maybe? Well things really become oppressive and eventually you want to leave after resisting arrest for a crime you didn't commit. You meet up with some smugglers/rebels. They show you that the earth has recovered somewhat. So you take some people, and go back down to the earth.
**That was the end of the dream. This is where i would go with that.**
On the earth you restart civilization on earth. Of course some of the remains are still salvageable, so you have a head start. Eventually, when it becomes clear that the earth is habitable and you and your group are alive, the artificial moon government try to invade. You fight them off and declare your independence.