(This is all a bit critical, but just to confirm I'm not writing this spitefully whatsoever.)
Gameplay wise it feels pretty tedious. Here's what I think may be causing that, and some possible solutions:
Movement speed is simply too slow. The walking speed around the planet could certainly use a big increase. The space speed could probably be doubled, and you could get away with even further speed increase on that by making the deflection off a planet even faster.
The respawn system is a little confusing. If you fall off the map, then you are given a choice to respawn at the starting planet and keep all of your progress. Yet, the second you become brown you're forced to entirely restart. The only consequence for dying is having to do the puzzle all over again. Which greatly adds to the tediousness. The easiest solution for the problems in the death system is to simply not have one. Especially for puzzle games, for puzzle games death systems are by default unnecessary.
There is no way to keep track of your progress on unlocking the planets. An indicator on the planet after you've unlocked it would help to keep track of that.
Onto other things:
I'm glad that there's a hotkey for the color pallet, it would be nice if there was a hotkey for the map and maybe even the controls as well.
Art wise I would recommend making the colors on the planets less saturated, meaning instead of them being a raw 100% neon color, instead tone down the colors a little until it looks relaxing to look at. The dark purple planet already does this.
It's a pretty fine puzzle design. Perhaps the color mixing is a bit nonsensical, but other than that it's a legit working puzzle.
The art for the player astronaut is pretty good.
While I think the respawn multiple choice system is a little confusing, I like the wording behind the accept fate option.
The music is pretty great, very great. It captures the atmosphere of a calm space puzzle well.