The concept is really unique and there's a lot of puzzles that come to mind that incorporate it. I think that I ran into the same problem as everyone else where turning up the gravity and heat all the way allowed me to skip most of the puzzles. I had some issues with the boulder puzzles, it felt like there was a very specific gravity I was intended to get it to but I couldn't figure out what it was. I liked the animation of transitioning between the planet and the character but after a few switches of it, I started to get a little tired of it, I just wanted to get the planet adjustments. So maybe make the animation play only at the beginning of the level. I also didn't fully understand that the sun could be moved in closer until I was clicking and scrolling rapidly in space to figure out what the arrow was talking about. I feel that this was a very ambitious and creative project and the scale (hehe) was a lot, I use unreal engine and can tell that a lot of work has gone into this. I think after implementing the changes people are suggesting here and watching some good playtests then you'll really be on to something awesome! You definitely have a good starting point.