Oh man, that was a work out.
The game is hard, took me like 5-7 attempts to beat it
The idea is really interesting, and the final stage really caught me off guard
It's a shame that charge shot mechanic deals so little damage it's pretty much useless, mashing the space bar is really pretty much the only way to play and not pull out all of your hair
My time is 46.65247 btw, let's see if any1 can beat it ;P
The battle music is extremely atmospheric.
Overall, a great take on the jam rules, really like how you made the limitations pretty much your main game mechanic, good job!
Also, props to you for writing your own engine!
P.S. the github link's broken