1: Ui is too bundled up. I feel like it is too close to each other, especially at the top right. Small nitpicking but definetly bothered me a little bit. The ui quality was not the best either.
2: Lack of tutorial. Putting a yellow arrow on the ground is not that helpfull. You should instead make it clearer by putting an actual tutorial that shows you where to go, what to click, and how to press.
3: Start with 2 diffrent (shape) parts earlier on. I personally did not want to continue for a while to unlock more gameplay on a game I probably would play once or twice.
4: Parts can drop faster? I dont think kids like to wait the extra second. (nitpicking.)
All in all the gameplay is great, but the visual stimulus, especially for children is not enough. I reccomend figma. You could also add a visual impact to the parts dropping, and making things a bit more goofy. ( If you want more children to join and not just older teens)