When the game boots, this folder is automatically scanned for VPK files or
subfolders. Each subfolder or VPK is added as a search path, so the files
inside those VPK's or subfolders will override the default game files.
See gameinfo.txt for more details.
For example, you might have the following file structure:
tf/custom/my_custom_stuff/ <<< This subfolder will be added as a search path
tf/custom/some_mod.vpk <<< This VPK will be added as a search path
tf/custom/another_mod.vpk <<< This VPK will be added as a search path
Mounting a VPK to the filesystem is more efficient than adding a subfolder,
as each time the engine needs to open a file, it will need to make a call to the
operating system to search the folder. VPKs can therefore be searched by the engine
much more efficiently. Each subfolder is a new search path that must be checked each
time the engine tries to open a file. So, for optimal load times, always use VPK files
and don't make any subfolders in this folder!
Note that the following directory structure is NOT correct:
That will add the directory "tf/custom/models" as a search path, in which case the
file my_model.mdl actually exists at the root of the game's virtual filesystem.
Instead, you would use something like: