The gameplay is good but I feel little satisfaction in completing it despite it being genuinely difficult. It's difficulty had me believe that I would feel as if I had triumphed once I won, I'm not sure why but it leaves me with a feeling of emptiness unlike other games like it. Also the balloon seems kinda janky, Im curious as to how you programmed it to interact with the...bird...thing? I've read your Diary thing you have linked in the description, I like that you're sharing your process with us and it lets me appreciate this game a bit more. I wish you luck with getting better at evoking emotions with your games.
ps- I think a good end state would be that the bird guy would sit at the cliff watching the balloon slowly float away while the final human on the human counter dies, so nothing is left but the single balloon the player put so much effort into saving. The music would play and the credits would roll over the scene and that would be the end. I know this suggestion isn't worth much now but I just wanted to voice my thoughts and stuff. Sorry for the long review .