A city that did not pay the piper, and when he returned he took everyone from the age 9 and up, leaving only young children behind. The months following many of the young children died, but some survive, creating small gangs and turning feral.
A few generations later, and the city is inhabited by the descendants of these feral children, still operating in gangs, and leaving vast areas of the city uninhibited. They are still mostly feral, each gang creating its own language, culture, belief. Some small groups of humanoids and wolf packs have also moved in. It is basically a mega-dungeon that is above ground.
Can you describe 5 gangs, their beliefs and attitudes, methods of communication, how they interact with other gangs, how they get food, etc. Are they still human beyond the physical level, whatever else might interest you?”