Controls and movement felt shockingly good for a game jam game. Punching was also very satisfying. That's quite impressive as it can take a lot to get that right.
There are also a few things I thought were quite cool in this game. For instance, I think what you did in the Title screen where you punch the rock to start is actually really clever. It's both a "tutorial" and a cool intro that reminds me of old arcade games.
There are however... SO MANY ROCKS. There was stuck at 9 rocks for a very long time, and there were a few moments where I saw some rocks in tricky to get to locations and was like "Ah! So that's the one the devs wanted me to get to." I had a few "platformer puzzle" type moments where I would try to figure out how to get to that rock... only for it to be empty.
I think some indication of where the necessary key rocks are could help. Maybe a little glow or slight change of color. Or... another option could be just putting more keys. Since figuring out how to get to some of the tricky rocks is actually pretty fun. It feels like you guys put a lot of thought into some of the paths to these tricky rocks. It's just that finding out the rock is empty is kind of disappointing.