Wow, this was a fantastic and cute little puzzler! Not even quite sure what to say: overall the experience feels very well-crafted in all aspects and I immediately got addicted and just kept on playing! It was quite challenging to rewire my brain to start combos using numbers instead of 1 and 6, as well as utilizing loop-arounds and reverse order. I do like some of the subtle things like how, if you're in the middle of building a combo while time runs out, it will immediately spend your current combo instead of just making you lose. The satisfying way building higher combos results in higher-pitched sounds is a classic, too. Well done!
If I had any complaints, it might be that the tutorial is a bit too quick, only explaining the bare essentials. Don't get me wrong, I like how lite it is and understand that a big wall of text of all sorts of rules will immediately fly out of the players head, so its better to just get to the fun stuff, but I had a lot of confusion understanding why sometimes I was suddenly able to chain similar numbers, and what the heck the gems do and how they are created, and so on. But then again, I feel like I did learn everything about the game, so maybe it was alright and I'm just being silly? But still, even if you don't make it part of the tutorial, I wish there was some sort of optional 'how to play' or 'codex' menu I could willingly access to learn the deeper aspects instead of just relying on potentially washing some of my games to experiment and learn.