It's very nice!
I was confused what the point of having the crown in there was, and why it's kingdom themed. "Decay" didn't really seem to be involved here.
It felt just like tetris, but more unforgiving, because there's no extra time to rotate a piece once it's hit the end, and there's no visual indicator of where your piece will go, so you just have to eyeball it.
It's a well made game and system, especially for a jam! but to me it did really just feel like tetris.
I hope to see it polished because I'm super curious about the kingdom part :)
-D