Based on an idea I had while doing something unrelated earlier today.
Arrow keys to move, Z to shoot.
I wanted to make it so my head would only appear on screen while commenting on your performance, and then have a secret boss fight if you shoot me enough, but I'm already 40 minutes over the limit and I haven't even started on that stuff yet. The floating head tracks more stats than you might think, although it only ever comments on your ratio of enemy kills. It compares how well you've done during your current life to how well you've done in the rest of the game so far, basically.