L4D2 Level Design/Add-on Notes
From Valve Developer Community
This summarizes the changes for Left 4 Dead 2 Add-ons.
AppID
The addoninfo.txt file in your L4D2 add-on must have the proper app ID:
addonSteamAppID 550
If this isn't included, or if it's set to the Left 4 Dead 1 ID (500), vpk files will not install themselves properly when users double click on them.
VPK install
If users double click a .VPK while the game is not running, it gets copied to a temporary location under
Steam\steamapps\SourceMods\addons
When L4D1 and L4D2 are launched, they look for the addons in those directories and copy them to the correct location in their respective addons folder.
See also
