The sections are randomised right? That's pretty neat, makes every playthrough more challenging.
After jumping for a few minutes, I finally got the dark heart. I think this is a nice lil platformer! What I would do is add more mechanics, such as launch pads, maybe disappearing clouds, anything! But I get that you had little time.
The graphics are well made, and the controls pretty good too, the only thing lacking really is the Theme/Innovation aspect, you could've made the game more unique, I encourage you to experiment more!! The random generation is nice tho.
Very nice game, GGs