I saw your note that this was done in 20 hours - damn impressive work! The cuteness you went for definitely lands and it reminded me of the autoscrollers of yore.
If I were to add one thing it would be a slightly larger hitbox for the ballon itself (or increased radius on everything else if you're using a single point). Sometimes I would be a couple of pixels away from a passenger and feel like I'd have given me the point!
That's a nitpick though, overall it's nice presentation and a refreshingly non-'jet pilot fights aliens' take on the format. Good work.