Fun game! And frustrating but it's right on point!
The movements and animations are super clean!
Only one negative aspect : your function onGround (or whatever you named it to detect if the player is on the ground) doesn't work very well.. When you are on the edge of a platform, very often, the player do the "second jetpack jump" instead of the natural jump. Which is annoying when you are on a precise platformer game, it forces you to jump before the edge which is annoying and counter-intuitive...
despite this, it was a cool and solid idea!