Structure
The game engine is structured into two distinct parts. The core engine handles and defines the Entity Component System design, the Messages pattern, and shared resources such as geometry. The standard library provides useful common components and systems, such as rendering to a WebGL2 canvas, an interpolation system, a simple physics movement system, and more.
Headers
You can see this structure in the headers for the library, it is structured like this:
game.hpp
message/message.hpp
geometry/vector_2d.hpp
standard/2d/sprite/sprite.hpp
As you can see anything that is in the standard/
directory/path is in the standard library.