That is really simple web game that runs from browser, you can do some cool stuff there like adding balls, changing size/color of a new balls. TBH I made that to learn more about inheritance and polymorphism in OOP. You can use it as example for something idc. I already have and will have bigger projects. Have fun :)
Game looks like that:
Also balls and rectangles can bounce from the walls:
Here is example of adding balls, fun right?