Very interesting concept. I love mechanics that are in this game, you really made something unique. I also dig sound design. Sounds of hits, monsters, attacks are fitting for music and ambient. Tank controls are perfect for this game, see no reason to disable them. Hope to see more "hidden" text that is only visible to us, the ones viewing from camera (such as "aim for the head" in the beginning). Perhaps this text will be very well hidden, but if you find it, you can get some story "spoilers", such as warnings of incoming danger. Or it could be some sort of lore of us, entities that control camera. What are we?..
Anyway, I enjoyed this demo very much, thank you. Looking forward.
I wish you luck in developing this game, please keep doing what you do.