The computation-heavy simulation part is written in C++ using GDExtension, the rest in GDScript. This allows for fast processing and easy extendability, while keeping the code readable. The last Godot ...
Note: Are you developing with Godot-3 ? If yes, you are on the wrong branch. Please go to https://github.com/Lecrapouille/gdcef/tree/godot-3.x instead! This ...