Ludii is a general game system being developed as part of the ERC-funded Digital Ludeme Project (DLP). This repository hosts the publicly available source code for Ludii. A precompiled build (Ludii.JAR) can be downloaded from Ludii's downloads page.

Working with Ludii's source code requires Java Development Kit (JDK) version 8 or higher.

1. Clone (and optionally fork) this repository.
2. Import the whole Ludii/ folder to your workspace.
3. To start the GUI, right click on /Ludii/PlayerDesktop/src/app/StartDesktopApp and launch it as a Java Application

Eclipse should recognise each folder as a separate project and automatically apply the -parameters compiler flag.

1. Clone (and optionally fork) this repository.
2. Import the whole Ludii/ folder as an Eclipse project. We recommend following the official instructions on importing Eclipse projects. Make sure to import each capitalised folder (AI/, ..., View Controller/) as a separate module.
3. In Settings | Build, Execution, Deployment | Compiler | Java Compiler, under Additional command line parameters, type -parameters.
4. To start the GUI, create a new run configuration under Run | Edit Configurations | + | Application.
   1. Set the module to PlayerDesktop and use java 1.8 or above.
   2. Set the main class to app.StartDesktopApp.
   3. Change the working directory from .../Ludii to .../Ludii/PlayerDesktop

Every time you want to run a class, edit the run configuration such that the working directory is .../Ludii/%Module%/ as opposed to .../Ludii/.

1. Keep in mind that each capitalised folder is meant to be a different module/project.
2. The Core module needs to be compiled using the -parameters flag. It's also okay to compile all the modules with it.
3. When executing a main method, set the working directory to the class's module, not the Ludii folder or the file location. For example StartDesktopApp should have as working directory .../Ludii/PlayerDesktop.

The main method to launch Ludii from your IDE is located in /Ludii/PlayerDesktop/src/app/StartDesktopApp. At this time we do not use any more sophisticated build tools (such as Maven) in our day-to-day programming with Ludii. There are some relatively simple Ant build scripts, but we only use these -- specifically, the /Ludii/PlayerDesktop/build.xml script -- for generating the releases published on the Ludii downloads page.

We have various other resources available at the following links:

• Ludii Tutorials: various tutorials on aspects ranging from game design (using Ludii's game description language) to programming with Ludii as a programmatic library. The source files for these tutorials are also available on GitHub.
• Ludii Documentation: the Ludii downloads page provides links to additional documentation, such as the Ludii User Guide, Ludii Game Logic Guide, Ludii Language Reference, and DLP Database Guide.
• Ludii Example AI: an example project for implementing Java-based AIs that can play Ludii games.
• Ludii Python AI: an example project for implementing Python-based AIs that can play Ludii games.
• Ludii AI Competition: a supporting project for Ludii AI competitions.
• Ludii AI: a repository used to hold the source code of built-in Ludii AIs before the entirety of the project was open-sourced. This repository is now deprecated, since the source code is also included in this repo.

While we of course cannot guarantee that we will accept every suggested change or contribution, in principle we welcome contributions and are excited to see what you come up with! Please send contributions on GitHub as new Pull Requests, and provide brief descriptions of what has changed and in what ways these changes improve Ludii (or other aspects of the repo, such as documentation). Please ensure that any new or changed code follows the same code style as the rest of the repository.

Note: pull requests should be used for code or documentation contributions, but not for new games (i.e., .lud files). We prefer that new games are submitted through our forums.

When using Ludii's source code in any publications, please cite our paper describing Ludii: https://ecai2020.eu/papers/1248_paper.pdf

The following .bib entry may be used for citing the use of Ludii in papers:

@inproceedings{Piette2020Ludii,
        author      = "{\'E}. Piette and D. J. N. J. Soemers and M. Stephenson and C. F. Sironi and M. H. M. Winands and C. Browne",
        booktitle   = "Proceedings of the 24th European Conference on Artificial Intelligence (ECAI 2020)",
        title       = "Ludii -- The Ludemic General Game System",
        pages       = "411-418",
        year        = "2020",
        editor      = "G. De Giacomo and A. Catala and B. Dilkina and M. Milano and S. Barro and A. Bugarín and J. Lang",
        series      = "Frontiers in Artificial Intelligence and Applications",
        volume      = "325",
    publisher	= "IOS Press"
}

The preferred method for getting help with troubleshooting, suggesting or requesting additional functionality, or asking other questions about Ludii's source code, is posting a message on the Ludii Forum. Alternatively, the following email address may be used: ludii(dot)games(at)gmail(dot)com.

This repository is part of the European Research Council-funded Digital Ludeme Project (ERC Consolidator Grant #771292) run by Cameron Browne at Maastricht University's Department of Advanced Computing Sciences.