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The Spellsource card game engine, supports Hearthstone AI and simulation

Project description


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This is a simulator and game server for Spellsource, a community-authored card game, licensed under the Affero GPLv3.

Play Now: Download the Hidden Switch Launcher for Mac OS X or Windows to get a copy of the game client. Play online against others! No other installation required.

Developers: See this example notebook for how to simulate games.

Please see the Issues tab to report bugs or request functionality.


  1. Changelist
  2. Description
  3. AI Research FAQ
  4. Quick Start Python
  5. Quick Start Multiplayer
  6. Quick Start Contributing Cards
  7. Getting started with Development on Windows
  8. Contributing Cards


Read the latest changes here or the deployed changes on the website.


The Spellsource-Server project is a 2-player card battler that supports hosted, networked gameplay. It features rudimentary matchmaking, collection management and support for game mechanics that persist between matches.

See the complete code reference here.

AI Research FAQ

Please visit this FAQ for an example of interactively playing a match in Python using Spellsource. This example can help you get started poking around Spellsource.

Quick Start Python

The spellsource package creates a bridge with the Java-based Spellsource-Server engine. It provides a direct 1-to-1 mapping with the Java API.

You can explore commands available in the package using this command:

$ spellsource --help

Usage: spellsource [OPTIONS] COMMAND [ARGS]...

  --help  Show this message and exit.

  change-password       Changes a Spellsource user's password.
  create-cards-db       Saves a cards.json database for the client.
  create-user           Creates an AWS user named USERNAME.
  fix-merge             Fixes card catalogue merge issues.
  format-cards          Formats JSON card files.
  hearthcards-stubs     Creates stubs from the Hearthcards.
  hs-replay-matchups    Prints a table of HSReplay matchups in TSV format.
  image-stubs           Converts images to card stubs.
  markdown-to-textmesh  Renders a Markdown file to TextMesh markup.
  replicate-database    Replicates mongo databases.
  run                   Runs the server.
  simulate              Run a simulation using AIs of a given deck matchup.
  update-dbf            Updates Hearthstone IDs.
  update-decklists      Updates the deck lists from Tempostorm.

You can also use the spellsource package programmatically. This requires Python 3 and Java 12 or higher (only Java 12 tested). To get started:

  1. Install a Java JDK.

    • On Windows: Visit this link for the latest OpenJDK builds.
    • On macOS: Install brew, then brew cask install java.
  2. pip3 install spellsource to install the latest version of the package. To build from Git, use pip3 install -e . to install the package from the root of this repository, and run ./gradlew net:shadowJar to build the engine.

  3. Start a game and play it with the specified bots:

    from spellsource.context import Context
    from spellsource.playrandombehaviour import PlayRandomBehaviour
    with Context() as ctx:
        game_context =
        behaviour1 = PlayRandomBehaviour()
        behaviour2 = PlayRandomBehaviour()
        game_context.setBehaviour(0, behaviour1.wrap(ctx))
        game_context.setBehaviour(1, behaviour2.wrap(ctx))
        assert game_context.updateAndGetGameOver()

Visit GameStateValueBehaviour to see an implementation of a complex AI bot in Python. This is a direct port of the Java code. Unfortunately, on the Python platform, remoting (accessing the Java engine) in the particular way this bot does is slow. To implement more sophisticated bots, consider adding a method to GameContext that will extract the exact data, in a binary format, that you need in your Python implementation, to reduce the communication overhead between Java and Python.

Quick Start Multiplayer

  1. Download the Hidden Switch Launcher for Mac OS X or Windows.
  2. Download the Spellsource Client from within the launcher and start it.
  3. Enter Quick Play to play against a bot, or Matchmaking to play against a random opponent.

Quick Start Contributing Cards

If you'd like to contribute or edit cards, write new game mechanics or improve the server, visit the Windows Development Guide.

Getting started with Development on Windows

Visit the Windows Development Guide for more about Windows development.

Contributing Cards

Visit our website for more about contributions, including guidelines.

Special Thanks


YourKit supports open source projects with its full-featured Java Profiler.

YourKit, LLC is the creator of YourKit Java Profiler and YourKit .NET Profiler, innovative and intelligent tools for profiling Java and .NET applications.

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