Cool simple platformer with tight player controls and feel though the art could be worked on a bit. Almost thought it was a rage game because I thought I had to collect all collectibles in a short amount of time.. But then I realized I could just cheese the game by skipping collecting the collectibles and go to the next level. The problem is there isn't really an incentive to pickup the collectibles.
Maybe when you collect collectibles lore about the world is unlocked. Or maybe you could have some sort of grading system where the player either has to beat the level in a very short amount of time, or the player has to collect the majority of the collectibles. I don't know, just something to make it interesting or provide incentive.
Regardless the game fit the theme and limitation and the player controls felt really nice so you did a good job. I enjoyed the game while it lasted! :)