The idea is good, the execution however, not so much. I like what you tried to do, and had I not encountered a lot of game breaking aspects I would've rated it well based on the idea alone.  main issues is the dash felt like sometimes it just didn't want to work.
I felt like my timing was good with the shots but that didn't translate well to the screen. My biggest gripe was enemies being able to just lock you in position and you can't use the dash to escape as I would've expected.  nice effort though and with more time and issues addressed it could be a great concept for something bigger. 

Nice decision in making an isometric survival shootem up with a rhythm based element. The shot gun works ok, the dynamite doesn't seem to do anything when it explodes. Also having the dash works to a degree, but when you are getting damaged to an enemy it just cant seem to escape from it even when I used dash. And when a group of enemies get close to me I keep getting stuck and couldn't move and I die very quickly. Might I suggest turning off physical collision on enemies while getting hurt by walking through them.

I like the idea of shooting to the beat! The music is good too.