If you’re making a mod that extends the game, it’s recommended that you keep the original game files unchanged, and put your files in a new data directory, which you can tell the game to use using the resource path command line -p (you also need to include the game’s resource paths Data;CoreData). This makes adding, removing and combining mods easier.

You can also package your mod using the Package Tool, and use it with the -pf command (you also need to include the game’s package DataPack.pak). It’s recommended to use the compression option -c to reduce file size and loading time.

Note that resource paths and packages should have unique file paths.

Steam Workshop

Mods can be automatically installed using Hellbreaker’s Workshop.

Creating workshop item

The first step is to create a workshop item definition file. The definition file is a Deco text file, and it looks something like this:

Your mod's title
Your mod's description
path/to/your mod content directory
preview image.jpg


  • The content folder path is relative to the definition file.
  • The preview image’s format should be something that Steam accepts (example: PNG and JPG).
  • Make sure your text editor uses line-feed line ending, for the Deco file to be parsed correctly.

Inside the content directory the game will look for:

  • Data directory to add as a resource path.
  • Data.pak to add as a resource package.
  • Levels directory to search inside for level files.

After your mod is ready with content and a preview image, you can upload it to the workshop by drag-and-dropping the definition file onto Game\Tool\steam_workshop.exe, or pass to it the path to the definition file as a command line parameter. When the workshop item is first created, a published_file_id entry will be added to the definition file so the item can be updated later on.

Workshop item example.