I love the idea and gameplay implementation on this one! Pulling and cutting the toilet paper feels really good with the mouse movements. That feeling is very well delivered.
It took me a few tries before I got the hang of it, but when I got it, I entered flow state and was able to count like a god. I was unstoppable.
Then something really interesting happened. I had enough so I wanted to lose on purpose, so I just pulled all the toilet paper in one go, but I noticed that the game actually counted that move??? That's when I realized that it accepts ANY multiple of the number it was asking for (luckily enough that number was 10 at that time). That's super cool because it turned from a counting game into a math game. Once you know how many slices of paper there are, you can math your way to score a lot of points in just one go. I loved that "aha" moment.
I really think you can scale the game just by making the "sets of" number even higher as levels pass, and making a way for players to notice that awesome math mechanic.
Congratulations on making such an engaging game! :)