There's a lot of code that goes into creating games. Instead of accumulating it all into one big project, we broke things down into smaller libraries and tools that others may find useful.
In the end, only some of our games are closed-source. All of our libraries and other software are 100% free and open source! We encourage you to use, study, and share our projects.
If you'd like to get involved with our open source development, check out our Developers page.