Checked it out. Works good. But there are some repeating exercises. On one level I got 4 consecutive "10-8" or something similar. I think it would be better to not show duplicate exercises, at least on a single level (if it has been solved already, of course).
- A way to skip to higher level at the start—like maybe an Easy, Normal, Hard difficulty level like in video games.
- CSS themes to make it aesthetically neater. Like a ninja background image, you-got-it-correct animated elements, etc.
But yeah, cool hobby project for sure.
I am actually building it for my son to practise, so hopefully I will work on this for a while.