Very nice demo. The controls feel great and the visuals are nice. The boss is difficult, but beatable once you learn it. I found it just the right difficulty (though I did resort to kiting a bit at the end). I only have one complaint: I found it very easy to accidentally activate the lock-on button by pressing the left and right mouse buttons at the same time, since it's set to the middle mouse button. It also seems I triggered a visual bug at 24:30 in the video.