I liked how secrets were a main mechanic of the game! Fun!

(I don't know your language, so please just throw my text at google translate so you understand it) x)


*Ahem*

That's pretty simple, but it does get the work done. The art is also fine and the character is adorable, so I'll give it that. 
The music is also way better than I was expecting, did you do it yourself? If so, then congrats!

I like the idea of the hidden keys, it does give an interesting puzzle aspect to the game. however most of them are hidden very poorly, you have to either kill yourself at least once or throw the character at walls until one of them isn't solid to be able to find them. You should have added something subtle to hint the player where those secrets are. (the famous telegraphs!)
Also, there's a lot of blind jumps, don't make levels where the player can't see what's below them.