Setup mod on Steam

To make a Source mod appear in your Steam library, its Game Directory (the one that has gameinfo.txt inside) must exist as a folder inside steam/steamapps/sourcemods/
. Its name, the assets it mounts, and the Source SDK branch it uses is controlled by gameinfo.txt
. When the player clicks the play button, Steam will launch the appropriate Source SDK Base, which will attempt to load the mod's client.dll
and server.dll
from the /bin
or /bin/x64/
folder.
You can use Symlinks to help make the mod development process more convenient.


sourcemods
directory only appear after you restart Steam. Restart Steam by clicking the small 'Steam' button at the top-left of the Steam window, and then clicking 'Exit'. After it closes, open Steam again.Mod files
In order to launch your mod, the necessary files need to be created in your sourcemods
folder. The Source SDK 2013 GitHub repo provides some sample Game Directories for you in the game/
folder. These folders contain all the necessary assets, binaries and scripts for your mod, the most important being gameinfo.txt
, bin/client.dll
and bin/server.dll
. These Game Directories are automatically configured in Visual Studio to copy over the dlls to their respective bin/
folder. This is done in the post build step (see Change output directory on this page).
- Singleplayer: Copy the directory from
<your mod>/sp/game/mod_hl2
(ormod_episodic
) to<steam_path>/steamapps/sourcemods/<your mod>
- Multiplayer: Copy the directory from
<your mod>/mp/game/mod_hl2mp
(ormod_tf2
) to<steam_path>/steamapps/sourcemods/<your mod>
Restart Steam after this step and you will find your mod listed in your Steam library.

mod_
directory to the sourcemods
folder instead, as changes done to the mod_
won't be synchronized with the mod folder created inside the steamapps
folder.Alternatively, in place of the sourcemods
method you can drop the directory into the original game's root directory, though this requires use of the -game
launch option.
Symlink mod directory
It would get tedious to copy over the mod directory every time we build our binaries, so instead we can symlink our mod_ folder so that it is always up-to-date. First, delete the folder we created in the previous step under sourcemods/ (if you have no other mods installed, this directory should be empty now).
- Open up your command prompt or terminal.
- Navigate to directory <steam_path>/steamapps/sourcemods/
- Create a symlink to your mod directory
- Windows:
mklink /J <mod_name> "<path_to_source>/<sp|mp>/game/<mod_hl2mp|mod_hl2|mod_episodic>"
- Linux:
mkdir <mod_name> && sudo mount --bind <path_to_source>/<sp|mp>/game/<mod_hl2mp|mod_hl2|mod_episodic> <mod_name>
Now, every time you update assets or rebuild your code in your game/mod_
directory the changes will automatically be there the next time you launch your mod.
Change output directory
You can change the output directory of your binaries to something other than mod_hl2
, mod_episodic
or mod_hl2mp
by right clicking Project -> Properties -> Build events -> Post build events and changing the paths as desired. This must be done for both Client and Server.
Example:
if not exist "..\..\..\game\MY_MOD\bin\." mkdir "..\..\..\game\MY_MOD\bin\."
copy "$(TargetDir)$(TargetFileName)" "..\..\..\game\MY_MOD\bin\.\$(TargetFileName)"
if ERRORLEVEL 1 goto BuildEventFailed
if exist "$(TargetDir)$(TargetName).map" copy "$(TargetDir)$(TargetName).map" ..\..\..\game\MY_MOD\bin\.\$(TargetName).map
copy "$(TargetDir)$(TargetName).pdb" ..\..\..\game\MY_MOD\bin\.\$(TargetName).pdb
if ERRORLEVEL 1 goto BuildEventFailed
goto BuildEventOK
:BuildEventFailed
echo *** ERROR! PostBuildStep FAILED for $(ProjectName)! EXE or DLL is probably running. ***
del /q "$(TargetDir)$(TargetFileName)"
exit 1
:BuildEventOK
Problems with running your mod
If, at startup, after the intro video, your mod crashes while Steam is active, but it runs without problem if Steam is shut down, then you follow these instructions:
- - to Open file steam_api.h (src\public\steam)
- - Find this and DELETE/COMMENT (Lines 551 - 562):
m_pSteamMusicRemote = SteamClient()->GetISteamMusicRemote( hSteamUser, hSteamPipe, STEAMMUSICREMOTE_INTERFACE_VERSION );
if ( !m_pSteamMusicRemote )
{
return false;
}
m_pSteamHTMLSurface = SteamClient()->GetISteamHTMLSurface( hSteamUser, hSteamPipe, STEAMHTMLSURFACE_INTERFACE_VERSION );
if ( !m_pSteamHTMLSurface )
{
return false;
}