In designated stations, there are humans that live in relative safety. However, outside these zones are pockets of Mutated Rats, and Spiderbugs, all of which will make any human their next meal if given the chance. The Surface world is completely destroyed, and irradiated. Among these threats are Communists, and Neo-Nazis, who both want to take over the entire metro station. Lurkers, small creatures, create holes that pose a danger to humans. If fallen into, lurkers will eat them.