Hey!
First of all, congrats for finishing the game! I was really fun and good looking game. I have some feedback for you and I hope you can use it to improve the game.
First of all, the audio part is missing, so the game feels very "dead". Some audio feedback would be great, when the player jumps, dies, collects a coin, etc. The other thing that bother me was the level design. The first time I opened the game I said "Wow, this looks so simple but cool". But there are some design mistakes, for example I thought that those spikes were part of the background, there was no visual information that I would be killed by those. You can make them red or something, it will be much better. The last thing I want to point out was that the levels are very unclear and there is no way for the player to know what is real and what not. For example, take the first 3 buttons from the beginning. Why the last one? It looked like the first and the second, only the color was different. Same with the fake platform.
So, in few words, I think it would be great if you can improve the visual language of your game, to tell the player what he can touch and what not.
Other than that, I think you made an awesome job! It was fun and with some updates I'm sure this game will be amazing! Congrats!
I would love to have you playing mine too, if you don't mind of course! ^_^