A minigun works well or use something powerful. Beating him with the war club won't do anything. Weapons that take a lot of life is the key.

You are given a lot of weapons and you can pick some up. Even if every shot hits the tyrannosaurus, his life will still be more than half full. You have to climb into the shot-down ship, and a minigun appears there. Keep shooting at his feet from the ship, but don't come out.

use invinceabilility and keep firing at bruckner

the easiest way to kill the final boss is to yous "fmnfb" or throw a lot of s at
bruncner.