This is a pretty fun game! I went into it reading the quick tutorial and was able to jump right in and enjoy myself. But when I came back and read the more detailed tutorial, it really impressed me how many details there are in each element of the game. (Pun intended) I didn't even know there were destructible enemy spawners! There’s a lot of depth to be found here which adds to the replayability and player mastery of the game.
If I had some feedback, I think the UI elements could be improved a bit. It would be nice to see the player and crystal health a bit more clearly and with a bit more feedback. (Random example: Maybe when you or the crystal are at low health, a sound effect plays) Also keeping track of score and time while playing would be nice as well.
Other than that though, it was a great time! Definitely give this game a play, it can be quite addicting! I made a video with my commentary and experiences. Great job and keep up the great work!