Cool idea, I liked the creative level design, especially the bubbles of cubes you have to break open to get inside. Also the time pick-ups are a good idea otherwise the timer would feel to frustrating.
The whole vibe, music and color scheme are also really nicely chosen.
Love the game over ":("
2 small changes that I would propose: its cool that the character controller accelerates and has momentum, but I would just make the movement a bit more responsive, maybe make the acceleration stronger but then cap the max velocity you can accelerate by yourself (that way the moving boxes can still push you beyond your own speed limit).
The other thing is regarding world visbility, the web player is really small and even when increasing the browser page zoom level you dont see a lot, I think the game would be a bit better if you could see more of the level at a glance.