Thanks for taking the time to give a detailed analysis!
Some of the problems I understand, since I knew about them from the start, but couldn't fix due to lack of time. You were probably confused with the hourglass mechanic because I didn't give a time warning just like you said, something to tell you when you're running out of time. It would have also helped to add a little shake to the hourglass when taking damage. In hindsight, I should have made sure to add them :^(
The bonuses text only showing one of them is a bug I overlooked, thanks for pointing it out!! <3
Some platforms are out of reach intentionally, but you can reach them by jumping from above! And there is a special blue upgrade which is stationary near the walls, which you can reach only by jumping from a higher platform. That upgrade gives you either multi-jump or a (kinda) special ranged attack! I could make a video showing how to do it probably, but no one asked for it yet.
I had lots of ideas for a story, with some bosses and stuff, but the time limit was quite a hassle, especially since it was my first 2d project :P
Again, thanks for reviewing it so thoroughly!! <3