Best jam game I've played so far, kudos! The art, cute character designs, and music are all fantastic.
I love the puzzle mechanics and how you used the countdown theme to force character swaps every 5 seconds. It's a great spin on the genre. It can get a bit tedious waiting for the timer to tick down so you can control the other character, specially if you make a mistake and need to backtrack. To keep the theme but fix the waiting, maybe you could add a "fast-forward" button that just speeds the timer up when we are waiting for the next swap? (but still that would be the same idea as swapping with a button just with a short delay), but again, this is a very good implementation of the countdown theme even with that issue.
Also, I encountered a bug where both characters would move and turn to stone simultaneously, which required a few restarts to fix.
All these aside, this is something I'd actually buy. Amazing job!