Tetrad is a flexible and easily extensible engine that allows designers and developers alike to make significant changes to gameplay and game structure at runtime.
Note: This project is no longer actively developed. If I were to make a game engine today, it would be written in Rust and built around the amlang project.
See the build instructions to get a working binary up and running.
Contributions to the core engine code are always welcome. See the developer docs for information to get you started.