The Dawn of the Homo Bestials
The Earth is no longer blue and full of life. It has become dark and turpid. No plants grow on it. After the 'Last Great War', all men were enslaved by a race created by the greed of man's urge for supremacy.
The surviving humans live far away from the cities in underground cities that are unaccessible to the new lords of the Earth. Some work for the new masters to do their menial jobs and the jobs that require brains and dexterity. The human male's ego was the cause of this all and now they are reduced to the lowest of the low.
However, young females have a status like no other humans have. They have houses in the cities and have access to the best clothes and fashion. Their only purpose and job is to feed the new masters' pleasure.
What?
Yes, the humans are slaves. The only surviving males are subjected to tasks that none of their new masters can do or fancy. Saucy females thrive as they are the object of the new masters' physical desires. This was a world built by men for men and the subjudication of females. The new masters continue to reap the benefits of man's follies.
Where?
The original planet Earth. Now called the Old Earth.
When?
After the Great Big War of AD 2027, the Earth perished beyond repair. If pollution brought it to its knees, then global pandemics and wars took it beyond repair. Those who created the Untermenschen Exterminata unwittingly killed almost every human and permanently mutated the other first order beings.
The Earth is no longer alive. It is dead and vicious. Only those who are meant to serve live. Others exist only to please.