All our sceneries special features and the whole GSX program, are written in the Python language, which allows us to do all sort of interactivity.
The Python25 zip folder contains some of the standard Python runtimes, which we include in the GSX folder, in order not to clash with another installation of Python you might have on your system (the free Blender 3d modeler, for example, comes with Python too).
And, we don't use the use the standard Python version, but a specific version optimized for realtime games.