| "I once thought I could save the world... now look at it"
— Spoilers for Deus Ex: Mankind Divided follow!
M13: G.A.R.M. is a main mission in Deus Ex: Mankind Divided and the only one to take place in the Swiss Alps. After Adam Jensen finds out that G.A.R.M. is now being used by the Illuminati, he sets out to find answers.
Get Inside the Facility Edit
Chikane will fly Jensen in and drop him off near a back door. Hack or use a multi-tool on the door, then open it. However, it seems Jensen was expected and a cutscene unfolds.
Escape the Facility Edit
After you come back around, you have to make a choice on who to contact: Jim Miller or Alex Vega. If you are going for the Foxiest of the Hounds achievement, you must contact Vega, since contacting Miller will cause an alarm to go off later in the mission.
After contacting whoever you wish, you will see several ways into the facility.
The straightforward way if you have remote hack is to use the breaker on the outside pillar to stop the fan, then enter the fan’s shaft and take the ladder that will take you directly to the ice drill control room. You can also remote hack the outside ladder, but if you want to use the drill you have to go down a hall with a camera to get to the room. Use a biocell to power up the drill controls. When you first move it to the rear (left arrow), use scold and the guy will believe you. Now move it left (up arrow) twice, then forward (right arrow). Once in that position, press the button to have it drill into the ice, tunneling a path you can use (drilling the tunnel will also net you the Core Driller achievement).
Now turn around and look up to see lasers in an opening. Use remote hack to disable them and expand the ladder. Climb up to the area, then jump onto the orange beam. Go all the way down to the ice drill but do not get onto the drill platform. Instead, center yourself on the beam you used to walk over and you will see the hole below you. Drop down and Jensen will land on the upper part. Move slightly to drop off again and he will land on the small lip to the tunnel. Careful here, as sometimes a guard will hear or see you doing this. Use the tunnel you made to take you into the second hangar.
If you do not have remote hack, you have to make your way through the hangar instead, either by attacking or sneaking your way through. If you sneak through the room, note the cameras and a turret in this hangar.
However you deal with the room, make your way over to the door in the northeast corner. If you have the EMP shielding, enter the room beside the door and enter the metal tunnel here, which will take you all the way into hangar two. If you do not, or are looking for the triangle codes, hack or use a multi-tool on the door into a smaller room that will lead you to a long narrow hallway. There is a small drop off area to the right of the path you can take if you are sneaking through. Get to the other end and pass through the doors into hangar two. If you contacted Miller, the alarm goes off as you enter the hallway (or the equivalent if you took one of the other routes).
If you took the ice tunnel into hangar two, you will notice you cannot easily drop off. If you have the leg silencers, you can use it here to not make a sound as you drop into the area, just be careful where you drop off as there is a guard directly below the tunnel.
If you wish to use Marchenko's killswitch, this is the first time you can find it (the second and final time will be during M15: Securing the Convention Centre). In the tent are some lockers in a corner. Climb on top of them (for those with klipsringer, you may need to crouch then jump to get directly on top of them) then hit the switch that is on the back of the lockers. This will open a panel in one of them, revealing the killswitch.
Make your way to the northeast corner, where you can either take the stairs or the elevator up to the third level. Go through the double doors and you will end up in a small room looking into a larger one with several guards. This area is much smaller so you will need to be careful here if you are sneaking through. Access the elevator here and it will take you up to the helipad. Jensen will be able to get a hold of Chikane who will then arrive to take him back to Prague.