Done! Actually did it in ex43b, however there’s a new requirements, which is to use more than one file, and use require to use them.
So I’ve modified my ex43b into ex45Project, it’s basically ex43b with the class files extracted out as a separate file, which greatly improve readability. Instead of scrolling up and down to look where the code leads to.
I will make more games like this in the future to further practice this concept.