In 2121, interstellar travel isn't a problem anymore. A group of students won a prize to travel to Kepler-452 star system. Right before they change their route back home, they receive news that the Earth has just been destroyed by a sudden worldwide volcano activity. They have to land on Kepler-452b planet, which is proved to be habitable for human life. As the leader, you'll have to help everyone start a new life and populate (Pregnancy) the New Earth.

(Please notice that there are no tentacles, aliens, monsters... in the story.)
Tyranny (Harem): You become a tyrant, have all women for yourself. The other men are your slaves. Democracy (Sharing): The society becomes a harmony democracy, where everyone has the chance to get laid. Anarchy (NTR): A guy not you becomes the new leader.

Under his rule, the society becomes a disaster (especially for you).