Really cool shader fx going on here, and a VERY neat concept. Simple, yet hard. The music is very simple, but has a lot of depth to it, and as a musician i´ve got to say good job man! :) Right from the bat i have 2 things that got into my mind. If the boss is going to have a healtbar that long, you should maybe make him evolve after he has 50 % hp left!, and even maybe change the mood of the track? The second thing was that, every now and then maybe the boss could drop coins which you can buy upgrades to either your health, armor or weapon? Or just make your weapon stonger if you manage to not loose hp or something. ( Like a manual machine gun or something, by tapping hitting Z & C after another to machine gun that boss down!). Keep working on this one, this could become something bigger than it is. Good job!