Nice work, I like the overall aesthetic, the color scheme and block design. The enemy challenge is good, it surprised me but then I was able to kind of trap it in the corner. I like the collectible design, although my first thought was that it might be an enemy. Since it wasn't moving I decided it was probably a collectible, I think making it a little smaller might help there, but I like the design. The jumps get progressively harder, one issue with a platform design like this is that's its easier in some cases just to jump into the void and start over than back track.