Here is the would be story line:

Very successful colonies have been established on the surface of Planet U, most having almost the same style of infrastructure as Earth based cities. However, recently, there have been sightings of Slimy Slugs with ball caps coming out manholes and Rock Monsters wielding half ton cast iron pipes. The outposts have since been evacuated and now need to be dismantled. The crew of the L.M.S. Explorer has been put in charge of the recovery of resources and clearing out the "Slimy Thugs" and "Rock Muggers." There are still some outposts in the evacuation stage, so traffic may interfere with the operation. Take care down there Rock Raider.

There would be ground types instead of terrains, such as icy for polar outposts, sandy for ones near the coast and in the desert. Pigeons would replace bats. And in case you haven't already figured it out, Traffic will replace lava.