This page in our trophy/achievement guide to Rage 2 contains information on Zipper silver trophy. You get this trophy/achievement for killing 13 opponents when using a zipline. The following description shows a demonstrative location where you will be able to get it. We also discussed step-by-step preparations and an easy way to unlock the trophy/achievment.
The following description of the trophy has a demonstrative purpose. You don't have to repeat all the steps at all cost. Zipper trophy/achievement offers great freedom meaning that it can be unlocked in various places.
The method we have described assumes that you will kill all 13 opponents using a Rocket Launcher. You can get this weapon in Strongbox Ark in Torn Plains region.
We chose Bridge Checkpoint location. This location is located in Twisting Canyons, the starting region. The enemies here are at level 2.
Once you reach the location, examine the hill above the correct location. Focus only on finding the zipline presented in picture 2.
Take out the Rocket Launcher and interact with the zipline. Look down immediately after you start sliding down. Shoot the rockets blindly. The rocket should hit from one to four or five enemies who stood on one of the lower shelves. It's important not to waste time aiming with the Rocket Launcher - you slide down pretty fast.
Don't kill anyone after you land on the ground. Instead, go to the nearest chasm. Kill yourself by jumping into the abyss - you won't be able to use Defibrillation skill.
This will respawn your character. You should respawn near the Bridge Checkpoint. The enemies killed with the Rocket Launcher are back, too.
Go around to reach the zipline on the hill. Repeat all the above steps until you unlock the trophy/achievement. Depending on how lucky you are with launched missiles, you will probably have to repeat these steps about five times.