You have a README which is great, but you'll need a License file as well (these are two main criteria for open source category).
The physics in your game are really great. Well done - it's hard to get that working. Graphics, artwork, and colours all fit nicely. I'm enjoying the sound effects. Maybe add some music too to make it a little more engaging.
Liking the background colour changing. Interesting take on the theme. Sometimes the objects in the "sky" disappear, is that intentional? Great job on your submission and rather addictive.