Hey, thank you very much for the detailed feedback and for spending time with the game!
Adding new mechanics as the levels progress is definitely something I would enjoy doing. However, I recently started focusing on making several small games in different genres to build a wider portfolio, so I intentionally kept the scope of this one limited and cut some ideas to finish it faster. Still, I agree that this kind of game benefits a lot from new mechanics appearing over time.
I did not think as deeply about the increasing ball count, but I spent quite a lot of time on the level difficulty and layouts. I used some formulas and shape analysis while designing them, so the progression, fairness, and satisfaction of the levels were probably the main things I focused on in this project. I’m glad they felt fair to you.
You should actually be able to access previous levels. On the level selection screen, drag the white current-level tile upward and the list should scroll back toward the earlier levels. It may not be clear enough, though, since you did not notice it.
An endless mode would also fit the game well, but I left it out because of the limited demo scope.
And yes, the plain blue loading screen looks a little rough. I usually create a loading scene early because I may later connect memory management, pooling, or other loading processes to it. This game actually has a short prewarm process, but since I was treating it as a quick demo, I did not spend time decorating that screen.
Thanks again for the careful testing and all the helpful comments. I really appreciate it!