Thanks for playing! There's a power modifier at certain breakpoints based on how much energy you use to charge, so spamming attack was supposed to be the least energy efficient. Playing through it again, it seems like the differences in damage were not big enough.
I could definitely improve it so that the changes in damage are more distinguishable. Maybe also provide different visual or audio effects to signal to the player that charging up a punch is the way to go.
Thank you, I appreciate the feedback!