I found the tutorial pretty clear! The only thing I didn't realize after the tutorial but much later was that the phase jump ability also damages the planets.
Other than that, fun game! Only other point of feedback is that sometimes the player ship can overlap the 'upgrade' button or the name of the planet, and then it is difficult to see where you are. Maybe make those more transparent when the player is near?
Also I found the 7th boss to be significantly easier than the 8th, which was a bit unexpected.