Very nice-looking game! I dig the circular inventory :). The multiple soundtracks with the combination of new colors made the game feel fresh on each planet :). The character controls quite well (sometimes I wanted to use arrow keys though :D), I definitely like the ability to sprint. The game window is a bit small, which is cool :), but I'm used to fullscreen ;).
I found it hard to craft. I think it has to do with the game having a lot of different "tables" (each with their own recipes). Since you loose almost everything each time you die, it is tough to experiment and find new recipes.
The enemies, while fun to try to dodge them :D, were pretty unforgiving. With practicly no indication they're going to attack and the ability to jump at you from offscreen, they felt a bit unfair.
And for the upgrade system, it has suprisingly many levels of depth: you have to collect XP to then level up to get skill points to actually upgrade. I think it could use some simplification - especially since the upgrades don't share the skill points, so there is no real choice - you just have to come in and upgrade (so this could be automatic?).
But hey, it's a very nice game :). From the encyklopedia I can see there is a lot of depth to the game! There is a ton of content everywhere you look, from the planet variety to things to craft. Big thumbs up for that! And generally, well done :)!