Really fun game! Please take my criticisms as nothing more than wanting to help a fellow developer because I really liked the game and art style.
1. Idk if it was something with my browser but the sound and graphics seemed not connected with each other at times (ex. the countdown time sound ended while the text was still at 3).
2. Jumping was a little floaty. GMTK makes a really good video explaining how to remove this floatiness because in most platformers the falling actually occurs quicker than the rising. It does not follow the rules of physics but that snappy jumping we like in classic games breaks the rules of physics. 3. At times it got frustrating because the next platform would sometimes be out of frame so I would have to multiple times take leaps of faith.
4. I did not realize there were lives until I finally failed. Possibly try and make it larger or more obvious on the screen for future games? This last critique you can take with a grain of salt.
Again, my game is not any better so I just wanted to leave my opinion as a play tester. Awesome work!