Awesome job! If you want him to get some experience with bug fixing, I found one: ask him what happens if you click on an attack and then hit escape (it cancels the attack but still charges up your attacks, so you can get to full charge on your first attack)
oh not "yikes" at all I totally peaked at the code to try to find one for him. I feel like bug fixing at that age is a fun exercise; it gets you thinking more laterally about the program you're writing.