Okay now that the rating is up I'm going to sound, WAY more critical, but I do that to help. Firstly I can definitely understand the frustration of things not quite working how ya want them to. And what I do have to say is that the particles on the boots coulda been a little better placed, it was a little too obvious that it was a particle system, and something like a laser thrust probably would have been better for the character at hand. For gameplay, and I'm not familiar with you engine so take this with some salt, you should have used simpler no physical hit boxes for your target, I think four would do it quite nicely. Now these would just be triggers, and simple boxes. One for the body, one for the thruster, and one for each wing. the body would have the least damage, the thruster the most. For the player character, a single box should work to tell if you hit the balls or not, maybe for the lasers that gun on the monster would shoot as well. Then for the balls them self perhaps some trigger, either damage or time to have them output would be nice. As for how you could do a rythym aspect like I talked about earlier, it would involve takeing the raw data of the songs and checking for peeks and valleys, have a damage bonus on the peeks, and a penalty on the valleys. If you can figure out a drop in a dubstep song, have the fire rate go up for your character, things like that. Now keep in mind everything I have said is based on my messing around in unity. where you'd do a 2d project, drop your monster in with a skeleton, attach your layers to the bones, put some box colliders on the appropriate parts, set thouse to is trigger. And when you write your code for the beast, put an ontriggerenter function in which you have the beast take an appropriate amount of damage. One more thing, the character you control would feel more in control if instead of going completely across the screen on an input they just went in that direction a little bit for as long as the control is held down and stayed in place when the control was lifted. Other than all that you have done an excellent job. Sorry for the block of text.