Great game except for the boss fight. Suddenly strange things started moving on the screen, and it wasn't clear what was what let alone what was going on. Then I was asked for a difficulty level. As I suspected problems, I set it to "Very easy". Then other strange things happened on the screen and nothing I did seemed to have any sensible effect. After a while I noticed some very dark, very big face(?) moving as I used the WASD key, and much later I discovered that if I click on certain colorful round things some missiles(?) emanated from it. But nothing I did seemed to change the lower (red) health bar from getting lower and the upper (green) healthbar from staying the same. When the red health bar ran out, everything seemed to be over, but I don't even know whether I won or lost.