This one's got some potential! Just a few thoughts:
While on my journey to complete basic math, I find myself having a bit of a hard time aligning the top arrow with where I want it and I think I know what might help, I notice the controls are kinda slippery; it's not as snappy as you'd expect it to be, but I think this could be an easy adjustment. Being able to hold down the arrow to smoothly move left and right actually feels like it makes things harder. I think players will enjoy being able to just manually tap left and right.
Also, I think I've seen puzzle games do a thing before where the entire selected column has some sort of highlight/glow to make it more clear what column you're picking, cuz you gotta keep up your momentum and having to manually check where your arrow is up above and looking all the way back down to see the blocks takes just enough time that it makes it harder to get much done.
You know the "next" number block on the right side? I think if it was also color coded like the blocks already in game that would help a bit too. I think the music and art could get a lil bit of a boost as well, currently it's all "okay", but maybe you could find a specific style that stands out a bit and dive deep into it, whether it's something futuristic and synthwave-y, or more urban with bricks and graffiti and a more jazzy or hip-hop soundtrack, or maybe something very "Y2K" aesthetic like CROSSNIQ+, which funny enough is also a puzzle game!
Nice work so far!!!