Survival games are a subgenre of action video games set in hostile, intense, open-world environments. Players generally begin with minimal equipment and are required to survive as long as possible by crafting tools, weapons, shelters, and collecting resources. Many survival games are based on randomly or procedurally generated persistent environments; more recently, survival games are often playable online, allowing players to interact in a single world. Survival games are generally open-ended with no set goals and often closely related to the survival horror genre, where the player must survive within a supernatural setting, such as a zombie apocalypse.