Great concept and even more great implementation!
Art is cool, mechanics are there. It's interesting interact with windows and jump around trying to break things!
As a previously frontend developer, I had shiver once I saw something like flexbox align in articles in level4 (I guess?...).
People mentioned about "dying" but it's not much a deal once you get used to it and understand why it's happening.
You've made a strong submission which is deserve to be very hight in a jam's ladder!