You can always write a custom "user.sh" script and mount it to '/opt/scripts/user.sh' inside the container to install all your mods, the user.sh is executed always as root and executed before SteamCMD starts, so it should be theoretically possible to install it like this (keep in mind that the game needs to be first fully installed): #!/bin/bash su $USER ${STEAMCMD_DIR}/steamcmd +login ${USERNAME} ${PASSWRD} +@nCSClientRateLimitKbps 50000 +force_install_dir ${SERVER_DIR} +app_update ${GAME_I