Maybe I didn't play the game enough, but where are the timing mechanics? Perhaps the idea was that you need to dodge bullets—and that counts as timing—but the execution is weak.
Either way, I really liked the idea; I gave it 5 stars for the concept.
Viewing post in Crystal Beats jam comments
I hadn't a lot of time to make a good tutorial, each enemy type (Rubis, Citrine, etc) has an instrument and a rythm playing on top of the music, that's why they pulse in a rythm.
If you shoot them in rythm, you inflict them damage, if you don't match the rythm you won't do any damages.
You can succeed by spamming the shoot but most of your shots will do nothing, I also disabled the penalty when it's a wrong shot (not in rythm) otherwise casual players would have a too much hard time.