Very cool! I really like the retro aesthetic and artwork. I'd love to hear what the music for this game would be.
I had fun playing it, and didn't think it was too difficult. Being in the middle of the screen stuck out to me; it feels awkward, especially since the level progresses to the right. I'd like to see the camera offset a little so you can see further ahead, even if it's just as simple as in Super Mario Bros.