Brutal doesn't begin to cover it. The goal is to kill all the men that appear in as many ways as possible. The preferred method is to attempt to catapult them into the air where there are many razor blades and spikes that pass by. There are also razor blades at either end of the screen and you can use the catapult to push the piles of bodies into them. Just do not push your catapult into them because it will destroy your catapult and you will fail the level. Collect the coins that appear after a number of kills and use them to upgrade your killing abilities.