Valve recently updated Left 4 Dead third-party support, providing players with more user-friendly methods of playing custom campaigns. Most people will be satisfied with hosting or joining local servers (i.e. games hosted on players’ home computers), but some players will be interested in playing custom campaigns on dedicated servers.

This brief guide will only cover campaigns packaged in the .VPK format. For technical information on .VPK files, read the VPK article on the Valve Developer Community wiki.

This tutorial is designed for server admins with remote access to their servers. Server admins with local access will need to make slight adjustments to the instructions.

Server-side Installation

1. Download the campaign. For this tutorial, I’ll use Detour Ahead.
2. Extract the downloaded archive file to any directory on your hard drive. In the case of Detour Ahead, the archive file name is 230609-bbls-detour.zip.
3. Open a FTP client. I use and recommend FileZilla.
4. Log in to your game server via FTP.
5. Upload the custom campaign .VPK file from your computer to your dedicated server’s left4dead/addons directory. Click here for a screenshot of the FileZilla user interface for this step.
6. Upload your addonlist.txt from your local Left 4 Dead install (default directory is C:Program FilesSteamsteamappscommonleft 4 deadleft4dead) to your dedicated server.
7. Restart your server.

Local installation

For instructions on installing custom Left 4 Dead campaigns to your computer, read the official Left 4 Dead blog entry Get your Campaign On.

Playing a custom campaign on your dedicated server

Depending on how you connect to your dedicated server, you may need to enter a preset sv_search_key after creating a Left 4 Dead Campaign lobby. If your server does not use a custom sv_search_key, you can skip this section of the tutorial.

To set your sv_search_key for a single session of Left 4 Dead and join your dedicated server:

1. Enable Developer Console. From the Left 4 Dead main menu, click Options, then Keyboard/Mouse, then set Allow Developer Console to Enabled.
2. Start a Campaign lobby. You must be the Lobby Leader for the sv_search_key variable to have any effect.
3. Open the console. The default key to access the developer console is ` (below the ESC key, above the TAB key, and to the left of the 1 key on most keyboards).
4. Type sv_search_key examplekey (where examplekey is the sv_search_key specified in your dedicated server’s server.cfg) and press Enter.
5. Click Start the Game.

If all members of your lobby have the custom campaign installed and if you installed the custom campaign to the server correctly, you should be on your way to playing a custom campaign on your dedicated server.