That was a fun experience! Outstanding how well you adapted the basic mechanic to the properties of each planet type. Nice, nice! Graphics and audio contemplate the mood of the game really well. It's a complete, polished and wholistic entry - well done! Btw, did you know that one of the first stories about traveling to the moon (The Unparalleled Adventure of One Hans Pfaall, E. A. Poe) was also about flying there with a baloon?
As for suggestions: More planet types... let's see... There are dwarf planets like Pluto and Makemake - so a version with little space might be thinkable. Gas giants like Neptun have extreme wind speeds and are fridgid cold - they could have a combination of ice + desert planet properties. Venus has extreme athmospheric pressure, which lets you move like being deep under water. Oh yeah, and water planets/moons of cause ... wow, there are so many possibilities and combinations out there. You guys know Melodysheep? - amazing videos on YouTube.
I'll stop here :-D Thanks for your entry and for hosting this fantastic Jam. It is always a unique, pleasant and enjoyable experience, thanks to you folks!