Coding wise the game is pretty simple. It has no real physics or anything involved and basically simple "Rectangle-Collisions". You can have a look at the source code (although it's pretty dirty with lots copy/paste involved during the hard time constraints).

As mentioned I did it in Monkey, but it should be also easy to recreate it in vanilla javascript, because all you need is a basic canvas you can render to, and there you go.

The real hard part was to get all the differents parts involved ready in time. For example the art took me alone around 10-12 hours because I'm really bad at graphics and I put a lot of effort and lots of trial and error in the animations.

The music I did in Logic Pro and Renoise, and it took only around 2 hours because I'm quite experienced in doing music (doing it since my childhood). But if you listen carefully you will find out that the arrangement is very simple, and it's also not mastered. Turning this in a full-blown-not-so-repeatedly track would take several days I think for me (I sticked to the 80:20 rule here ;).

The level design I did in Tiled, and I had the Tiled loader ready before the Compo started.