Fun But Easy
OK I'm gonna do this the easy way, pros and cons list.
Pros
-Great bow mechanics
-Nice variety of monsters
-Nice variety of skills
-Fun gameplay
Cons
-No achievements (because hey, they are fun.)
-Uninteresting weapons (until the last one with splash damage, which I only had for two levels.)
-Only 13 levels
-Too easy, especially for low amount of levels.
-No saving mechanic? I didn't see one at least.
Now for some suggestions.
-More levels, even if that means making a sort of harder difficulty (where you can keep the gear you earned).
-Different abilities on the bows, the last one had splash damage, but couldn't a bow carry freezing? Or DOT? Just some other choices to make things more interesting.
-Arrows seem to have very little use, I bought one upgrade for the arrows all game. Never felt like it was worth it after that. Maybe instead of the bows carrying abilities maybe the arrows should? That way low level arrows could have things like, faster fire-rate or +25% CS.
I'll be looking for the next game! I hope you do make a sequel as this was quite fun.