Thank you so much for playing and your detailed review! I'm glad you found the interface clean and the mechanics explained effectively—that's exactly what I was focusing on.
Your point about the contrast between the tiles and the walls is excellent. I understand that this can be confusing, especially in later levels. I'll keep that in mind and improve it in the update!
Your description of the difficulty curve is also completely accurate. I did encounter some difficulties while designing the levels, and I considered adding extra mechanics to increase complexity, but I ultimately abandoned that idea.