Good job! I love the art style, the level design and story. I only have a couple of complaints: the medals don't seem to work, I don't actually receive them when I unlock them in-game, and also there's a lot of typos ("devellop", "chapiter", etc) that you should look over. These are just technical issues (after all this is just a demo) and they don't take away from my overall enjoyment of the game.
P.S.: on what platforms do you plan to release the game?