Hey!
Gave your game a go, but couldn't get past the 3rd(?) level with the long red bridge thing. I don't really play platformers so that could really just be a skill issue, but I thought that my perspective would be useful as well.
- The disappearing ground mechanic is cool, but the execution is confusing. Its not explained what determines when they disappear and it wasn't completely evident from the gameplay either, at least for me. They sort of fade away gradually so its hard to tell what actually triggered it and when. I felt that hitting them causes the disappearance but I couldn't be sure.
- The wall jumping didn't feel very intuitive and I thought that it was weird that you could only wall jump on the coloured terrain.
That being said I thought that the music and sounds were very nice. The visuals were pleasing and coherent as well :)
Good job for your first game, keep making them!
This is also my first game jam :)