Congrats on the first game jam. I like the idea of having to fight monsters by using the environment instead of direct combat. However there's a lot of issues.
First off I got stuck in the Help screen with no means to return to the menu, I tried all the keys and there was no button I could click so I had to close the game and reopen it to play it.
The rocks are incredibly fast and appear with little warning, making them almost impossible to dodge. I see how this was supposed to create the lack of control by having to deal with falling rocks but because there's not much I can do about them I ended up just ignoring them instead.
It takes a really long time to kill the bosses so when I got immediately killed by the 4th boss I decided not to try again since there is no option to replay levels.
Finally the music doesn't loop so I had to close the game again in order to get the music back while playing.
It's a neat idea though, I hope you learned a lot making it.