This is really cute! Despite the simplicity and short length, I had fun with this. Being unable to actually move without a powerup, and only charging jumps is a neat game mechanic, and works well with the super cute slime design. I think having the jump charge faster would help the game feel more snappy and responsive, but nevertheless, this works quite nicely.
(Also I found the secret, it was cute to see you added a little easter egg!! Can't believe I was voted out....)