I'll open this with a disclaimer that I suck at puzzle games.
I really like the concept of this game. Match gems to use powers, it's neat and different and magical as heck. The intro is fantastic, the pixel art is nice, and the music and sound goes great with it.
I found this game really obtuse, to be honest, and the first round is so fast-paced that you don't really have time to figure it out before you died for some reason which greatly exacerbates the issue.
On my fourth try, after re-reading the instructions twice, I managed to figure it out. I still didn't get very far, because again, I suck at puzzle games.
There were a few mental blocks I had to overcome to get to that point:
1) It's not clear what each symbol does.
There's only a vague correlation between the appearance of each symbol and it's effect. It would break the gem theme a bit, but it would be much more obvious with more explicit symbols. I thought maybe it should show an animation when you match a symbol showing what it does, but see item 3 below.
2) It's not clear where matches happen.
I had assumed that only symbols lined up in the box on the right would be matched. But then I saw symbols inexplicably disappearing and the match sound playing. After a round or two I realized that a match anywhere in the ring counted. I then wondered what the heck the box outline was for. More explicit animations or graphics might help but I don't have any specific suggestion here.
3) It's not clear that you have to use your powers once you have matched symbols.
I assumed this game was broken for a good ten minutes. I kept matching the red symbol to do damage, but no damage was being done. I chalked it up to a glitch. Tried it again. Tried a different game mode. Restarted the game. Finally re-read the instructions and realize that you need to trigger the action with the spacebar. I thought the number in the middle was some kind of score indicator. Maybe this could be addressed with a stronger indication of hey, you need to take an action here.
There's one that I never figured out, but realized after reading the comments:
4) It's not clear that you can swap symbols between rings.
See number 2 and my false assumption. I'm not sure if you want this, to be honest. The game is already way complicated for its fast pace IMO, but once again, I'm not good at puzzle games so maybe it's just overloading my useless brain.
The other thing is I'd really like to see animations for the rings spinning. It's not a mental block thing per se, but sometimes it felt like things were just happening and there wasn't any illusion of motion.
Although I found it too complicated for me, I think it's a decent game once you get to the point of understanding how it works. Unfortunately, the game really doesn't help you get there as it stands.