I'll focus on cleaning the code and making it less glitchy (same for the art), then move onto making more stages until I have the full game. Thanks for your reply, I'll do my best . Also, do you mind if I post that video on twitter? It's great!
From the video you posted, that was version 0.9 (since there's no transition from the intro to stage 1) I think the boss should be less glitchy now and other small things are fixed. I'll keep trying to make the code better, or at least as bug-free as I can.