This is a neat little game! I have a few comments about it though that may make it better - take it how you will, but first, I wanna go through the good stuff:
1) Easy to learn mechanics - I think your game benefits from its relatively simple mechanics but you also have very short concise tutorial that was very easy to pick up.
2) Pleasant artstyle - I enjoy looking at this from the beginning your art direction works with the game you're going for, or at least your art direction works. Nothing too jarring or crazy at any time.
The game was quite fun as a whole, very simple gameplay and easy to enjoy. There were a few nitpicks though:
1) Not clear as to which are the obstacles - especially in level 3 (where I stopped) when the ships could also pop my balloon and I didn't know. I think you could benefit to adjust your art direction to make it more clear as to which are the obstacles and which are not. This will help players adjust accordingly.
The same thing happened in level 1 with the big grey power line towers, I didn't think they were obstacles until after I died and I realised it was shown in the tutorial. I just think the obstacles need better indicators.
2) Occasionally unforgiving obstacles - at the end of level 2 after the grueling multiples of spike launchers right before the end, there's just ONE more moving spike there. I didn't die fortunately but I think you would benefit from removing that.
In other words, your level design could use some more work to have better flow. Your level 2 has good flow, up towards a climax at the triple spike launchers then an ending.
3) Occasionally goofy controls - I think I understand how you made the wind mechanics work now. Because when I aim my wind gun upwards and blow the top of the balloon, it still pushes the balloon up (where in real physics, it would still blow the balloon down) - this is just a small nitpick, but if you wanted to take it further, you could implement more realistic physics.
Of more particular note, is the lack of a function to immediately flip the gun 180 horizontally. Scroll whell only controls make it difficult to make split second decisions when your balloon bounces off the top of a cloud and richochets flying towards the spike in front of me and I needed to stop it immediately but I couldn't because scroll wheel is too slow. Either implement a scroll-wheel sensitivity function, or the flip function - or both.
Very enjoyable game though. Well polished and I'm sure you've put a lot of work into this!
Kudos!