Leaf is a demo engine, mainly done as a fun side project, and used to release demos at demoparty events.
You can find more information on the project page: http://leaf.graphics
I work on this project on my spare time and don't plan on earning any money from it, so feel free to use the code however you want. It's licensed under the permissive MIT license (see the LICENSE file for details).
I would appreciate if you let me know if you used the engine or its code in your projects. There is no legal obligation though, it's just to satisfy my personal curiosity ;)
I won't accept pull requests for the moment (maybe later!). Right now, the goal is not to make a huge open source project, but to have fun shipping demos :)
Even if the engine is far from perfect or complete, it is still a reasonably efficient, working and shipping project, maybe looking at the code can be useful, especially if you want to dig in a smaller codebase than other engines out there, so feel free to explore or take whatever you want from here!
Please also let me know if you have feedback, found bugs, or think my code is nonsense, I'd love to hear about it :)