This is a really fun game. I like the presented mechanics, visuals, atmosphere and overall ideas going on in this, it's quite well done!
I did find the spike pop hitbox very unforgiving and spoiled my fun very quickly. Just barely grazing any spike from the side would pop/kill me and it made level 7 & 8 unplayable as you had to be positioned in exactly the right pixel for your balloon to pass through the required path.
Definitely a very challenging game, but with better collisions this would be a very solid complete feeling game.
Really fantastic work!