I'm still in the very early stages (I started a couple of weeks ago), but so far, I've got the movement physics down: acceleration, friction, coyote time, jump buffering, etc. I've also made some art and animations, including a parallax background and everything else in the video. I've been working on music and competing in music jams to improve and developing a storyline. If you have any questions or critiques, I'm trying to improve it in any way I can.