Finished it :-) Nice game! Could use a bit more variation perhaps, but still, very smooth and good looking. Found two bugs / remarks:
1. When touching a crystal you pick it up, but after picking it up and when it's floating to your XP bar, it keeps 'whistling' when you touch it
2. After finishing, I was level 16, when achieving level 17 I did not get an upgrade. It seemed to be every other level from then on. My planet was full though, is that the reason? Alternating between weapon and upgrade?