It is a bit short — expected in a game jam — but good. It has nice controls, the music is nice, if a bit repetitive at the end, and the graphics are well done.
I miss some constraint in the jumps or the number of bullets, because as of now there is nothing preventing me to double-jump all the way to the end while shotting at everything that moves. I’m guessing this is also the result of the time frame.
I would also make the introduction skippable: in one attempt i felt while it was still narrating, i had to wait for it to wait until i could start again, and had to read it all over.
Well done.