I definitely see why you would call this a "game" and not a "tool," but I think I can also see why the creator would disagree.
I think what the creator is trying to say is that if an app is made for a purpose (one that isn't entertainment), then maybe it can be called a tool? This app is meant to help you improve a practical skill. You use it to get better at arithmetic -- that's its purpose. This is different from something like Among Us, where the purpose is entertainment. (Yes, you might also learn a practical skill like deduction by playing Among Us, but that's not why you'd play it and not why it was made.)It does seem like a very permissive definition though. Is a hula-hoop a tool for cardio improvement? What about a jazzercise class? (If we keep this up, it starts to sound like another language game: is a hotdog a sandwich? what about a bagel? etc.)
In any case, I don't think the creator is trying to sneak this into the jam for more views or anything, it's just coming from a honestly different understanding of "tool."
Long story short: language is floppy, long live language.