Such an awesome game! I think I played a movement shooter in the past that had this sort of "attack on beat" mechanic, but it is no comparison to Hellsinger. I've been having tons of fun and it makes you feel like God when you go on a well-timed murder spree. I wish it was maybe a couple dollars less, as, it is a very short game (in comparison to most other high-quality titles nowadays- but I think with a bit more content added it would be a little more justified.
SOMETHING THAT I BEG THE DEVS FOR:
I'm not sure if this game is going to receive continuous updates, but something that I think would be AMAZING would be a workshop. I'm not sure how it would work out, and trust me I know that there is a ton of careful coding when it comes to the music, and when the vocals come in and everything like that, but I think if they could find some way to allow users to make custom songs and levels, it would be so killer. Maybe even DLC that features special guest artists and bands, although I don't really know how difficult that would be.

Anyways this game is really very cool, and I've had tons of fun so far.