While I don't mind gravity affected arrows (I actually prefer them in games), combined with charging your shot makes aiming and landing on your targets really feel like a chore. I've played a few rounds of this, and I still haven't really gotten the hang of the aiming/firing mechanic. To me, this kills all the fun that the game could have had.
Also, those graphics are painfully and blatantly done in the vein of Kingdom Rush. The colors, design, and shading/highlights/rendering is strikingly too similar to not have been an accident. Maybe its just me, but I'm not crazy about that style or copying it. I mean, even the hero concept is kind of taken and rendered the same way; both are using Londrina font and shaded pretty much with the exact same styles and saturations.
Anyway, I don't wanna rip all over your game (even though I kind of did): I can't enjoy the game for the shooting mechanic and even more so, the unoriginality of graphics is painful. There are plenty of ways you could have mixed this up. That being said, I still appreciate the amount of work that goes into these projects and I hope you guys learn from your mistakes and make better games.