 Multiple visual in-game hints—including license plates, park signs, markings on airport equipment, and lines of dialogue spoken by the survivors—suggest that these locations are in Pennsylvania, and similarly a memorial wall giving names of those who have died in the infection (actually names of the game's development team) along with their dates of birth and death suggests that the game takes place in October 2009.Each campaign is divided into five chapters (except Crash Course, which has two chapters, and The Sacrifice, which has three) marked by safe rooms, which are checkpoints where players can heal, re-arm and revive characters who were killed.Specifically, the four campaigns are