Truly a masterpiece especially concerning designing!
First of all I really liked the idea of the flying balloon, I don't know any other games including a hot air balloon, quite creative in my opinion!
It's also real fun playing it, especially when you get used to the control which was a little bit hard in the beginning to be honest. It worked for me very well, I didn't find any relevant major bugs although the map generates not fast enough (may be a minetest issue).
The whole setting is really convincing, asthetic choice of colors, flying gas bottles are of course unrealistic but isn't it a game? It's also kind of calming and because of the aesthetics it's not overstimulating at all (like many other games I know).