Walkthrough/Tips: Simple contract requirements that are easier said than done. Getting headshots with the StA-11 on the helmet wearing Helghast cops takes patience. And there is only one location in the level where you can get the zipline kill, its near the beginning of the level just after you finish your first firefight. You will come to an area where you can choose to go right and use the zipline or go left and sneak into the bunker. Obviously, take the right route and hug the wall until you get to the zipline. A sniper will be to your right so have the Porcupine equipped and ready to fire. Once you jump on the zipline turn the camera to the right a bit and fire a porcupine missile at the sniper to kill him.