| "Built that thing to be Zombie-Proof!"
This article is not canon. Dead Line is a creation made by the community, and not by Valve.
Dead Line is a Custom Campaign for Left 4 Dead created by Valve. It was released along with the SDK. It is supposed to be used for developers and mappers as a basic reference for making maps. A second version was made for Left 4 Dead 2 titled Dead Line 2.
- Dead Line 2's tagline: "Mind the Goop" gives a reference to Portals GLaDOS's line "Mind the gap".
- It ends with the Survivors leaving on a subway car.
- The maps can be played in other modes (Co-op, Survival...).
- Dead Line 2's second map is minorly broken, because the trains in the second map are invisible.