(Unsolicited game dev thoughts. Skip to the end for praise. :P )
Hmm... didn't the previous card-like version have a "how to play" menu item? Where did that go?
Separately, I had a thought about presentation. I can find it a little confusing to have the numbers under the tiles to be in the same part of the square as the number on top, and yet be referring to a different thing, while the number on top moves to the side. It's only a small annoyance, but I was thinking how to convey that better.
On the right, you have gems and roman numerals. What if, when you remove a tile, the number on the tile stays in the same spot, but its backdrop shows either a gem or an imposing roman numeral? Similarly, since you can place notes on tiles, maybe if you make those numerals look more scratchy and hand-drawn, and in the style of a gem or roman numerals?
Still, this is such an elegant little game. I still occasionally boot this game up after nearly a year of it being on my playdate. It's good. :3
(I wonder how a hex grid would change the deductions?)