Players start in their base, and then have to choose between 4 classes, each with different speed, weapons and start health. Each class will be very diverse and some have UNIQUE abilities or weapons. The level design has been specifically thought to give certain classes advantage depending on the situation, some vents shaft are only available to the scout class, while some Energy Core generator can only be deactivated with the gravity gun, and where some enemies such as the APC, can only be killed with explosives weapons, that only the Heavy and the Assault have. The objective of the campaigns, will be to explore every area, in order to find a specific object, to bring back to the base. Once all objects are gathered, depending on what the objects and their uses are, a Left 4 Dead Ish finale event will be triggered, and the players will have to defend their base until the escape is possible either via a rescue vehicle, or any other ways.