I like the concept of all stats being merged into one. I think that concept has a lot of potential, especially if you try to think of how it could be implemented in genres outside of twin stick shooters.
This was pretty fun for what it is. I really enjoy the music, and that even the tempo was tied into your overall stat. A great way to give immediate feedback into how you're doing. Its a shame that there is a controller requirement, as I feel the gameplay doesn't benefit too greatly from one. I also think that this will prevent some people from playing your game. But thankfully I do have one so I could check it out.
What impresses me most is that you say this is HTML5 / Javascript. Did you use a framework, or is this all vanilla? I learned game dev via JS, so it has a special place in my heart :)
Nice work!