Sparga

Sparga was a rare find in a hostile galaxy; a planet that was naturally inhabitable to humans… though some theorize it was previously terraformed long ago (but functionally the same thing). 

After the Coalition’s retreat, several different hostile alien species invaded Sparga. To survive, the Spargan colonists consolidated into a couple dozen Fortress Cities and a few hundred fortified Outposts. 

The city-state-like Fortress Cities have populations measured in the millions. They differ widely in their governance, methods of defense, and culture.

The Outposts function like the Fortress Cities, but on a much smaller scale. They have populations measured in the thousands. Outposts tend to ally themselves with Fortress Cities for protection. It’s no fun being the little guy.

The Fortress Cities frequently bicker with each other for resources, but full scale combat is avoided. The planet has made some moves towards peace and reunification by uniting much of the planets police forces into a single entity. In theory, the police forces are headed by an organization independent of any single fortress cities' influence.  

Travel between the enclaves of human civilization is difficult. Roads are often non-existent and hostile aliens prowl for easy resources. Communication between cities is also challenging as satellites are quickly fired upon.