So simple, but so fun! Loved collecting all the little secrets

It's pretty good all things considered! I'd suggest making the tongue longer and either making it grow at the tip or whip around a little bit to make the animation line up better with the hitbox. Healthbars for the bosses would also be beneficial. Story wise I think it would be better for the skeleton to be less in the know about who the little guy actually is so the fact that you're the monster can be a more impactful reveal later on. 

the black screen bug combined with how frustrating the wall jump is makes this otherwise cool concept into a game I can't recommend