Observation: DLCs are downloaded to your computer with the base game, suggesting that it is possible to unlock it without adding extra files.

• open game dir

• locate and replace the original steam_api64.dll with the file available to download below. (You may want to back it up first)

• add cream_api.dll in the same folder. Configure which DLCs to include by editing this file. You can get this file by going to the game page on Steam DB with this tampermonkey script.

steam_api64Download