Martian towers in Space 1889

[tshiggins]

I don't know much about the setting, though I've seen the books. I'd go with broken windows, myself, which (temporarily) created a haven for the local pigeon variant. However, that soon attracted the attention of a local predator, which raided the rookery and promptly took over the place. It doesn't have to be a flying predator, either. A scarier notion might be an arboreal-type predator that hunts the upper levels of the towers, by traveling across the connecting bridges.

That means the players will eventually reach a level with an avian or arboreal predator in an environment so hostile that it will try to make a meal of anything made of protein.