I love this concept! It was super fun. I'd love if the number of lives you have is displayed somewhere -- I ended up just running into the spikes as many times as I could to figure out my gameplan before I started playing each level.

I think the hardest part for me was figuring out how to jump to the exact height I needed to in order to be able to jump on top of it later. I kept getting it just a couple pixels too high. This made the level with the two spike walls facing each other super hard, because I knew I wanted to hit specific locations but I couldn't hit them consistently.

I made it to the level in the screenshot, then got stuck cuz my square couldn't squeeze into the hallway to reach the green flag (lmk if I'm missing a mechanic to make the square smaller) :( guess all the exercise made it bulk up too much for the corridor!

Overall, I had a blast! Thanks for sharing :)