Thank you for trying and I am sorry it gave you a rough time. People are finding the game difficult and I think it is a mix of high health enemy groups and the fidelity of drawing circles making it difficult to deal high damage.
It might be worthwhile that I look into alternate tools/ ways to attack for the player that still resonate with the game so there are more options for the player to fight back in addition to nerfing many of the levels. I appreciate you sticking with the game to level 16 and can understand why the game would get frustrating :)