Really good prototype! Funny soundeffects and interesting upgrades! One question: Doesn't the size upgrade make you more vulnerable for projectiles? I think this has a lot of potential. As a next step for improvement I probably would make it a little easier, because I was dying very early and felt that I had no chance to win the game or progress further. My highest score was 882, but only because I got early health upgrades and a full heal right before I was dying.
Still really fun to play. I definitely want to see more of it.