Thanks for the kind comments ^^
I was thinking on adding a progress and a parallax effect on background, and make an ending to the game, but I never tried to make the release build of the game so I was really very worried that I maybe could not build the game in time haha, so I decided to not implement them and just use the remaining time for building.
Indeed, is very unclear when the player get hit or not, the sound effect is very difficult to hear compared to the music, but I only noticed that days after the release.
I also loved the sprites, Leonardo (the pixel artist) made a really good art in this game.