Loved the art, very creative idea, very juicy!
Just a little thought: it's weird that you have basically two different life bars (one for the planet, that you can regenerate, and one for the player that does not regenerate). It could be interesting to differentiate the two life bars more, for example have the size of the planet influence your jumping height so sometimes you want you planet to be small to jump on higher enemies. Or just have one single life system (the size of the planet) and make the player immortal, but maybe when the enemies attack him you can have him be stunned for a couple of seconds (maybe precious seconds that will deplete your planet too much).
These are just some thoughts I got while playing the game, feel free to ignore them ^^'
Other than that this is a very well polished game, bravo!