This was great fun, seemed bit like a more actiony Quadrilateral Cowboy. Very strong goofs. The tab window was a nice touch, but it actually made the skull aiming hard because I had to look at an angle from where I wanted to shoot so I could then move the mouse to click on the skull shooting. (You can see that clearer as well as a weird collision bug in my video below)
I recorded myself playing, the video is here if you want to see: