Try this idea...
It blends
Steampunk with
Planetary Romance. One ten years ago, one of the few great inventors of the planet
Israfil planned the conquest of the distant past. He was going to send his vast armies of cloned cyborgs twenty-five thousand years into the past to conquer 19th century Europe. The plan was to take London, Paris, Rome, Berlin, and Vienna, all on May 12th, 1891AD.
The plan blew up in his face. His five vast citadels were overwritten by the five cities he meant to conquer. The cities, after a period of shock, stabilized.
Although the religious a philosophical problems haven't been figured out. Each city took over the territories around it. New technologies have been exploited. These transformed Victorians have a world to conquer and amazing new tools to do that with.