Okay, my time has increased to 17:33, and I can't go further. I figured out that there was an alien behind the tree. But still, when you get 2 guns, I doubt if you can actually kill Black Bull in about 5 secs (even with my button-mashing skills, it takes a slightly longer time than just 12 secs). But this doesn't answer my question. I still don't understand, (maybe even with codes), how you could defeat Black Bull in 12 seconds.