L4D2 Level Design/Add-on Notes
This summarizes the changes for Left 4 Dead 2 Add-ons.
The addoninfo.txt file in your L4D2 add-on must have the proper app ID:
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.
If users double click a .VPK while the game is not running, it gets copied to a temporary location under
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.