To what extent does game code go inside the create scene function?

Most games have extensive code that can’t use JUST Babylon. How much of the actual code goes inside the createScene() function?

Sorry for the long delay before a reply.

The createScene method is a useful way to set up a scene, particularly to transfer the scene to the playground. It is just a function like any other JavaScript function, a convenience no more. You are free to set up functions in any manner you choose. As for any function it is all a question of passing the correct parameters.