When the chapter begins, you're free to wander as you please. Your disguise means that not even the Kampfhunds blocking your path will be wise to you. Walk through the x-ray machine and salute the soldier at the baggage area. Crouch and move into the conveyer belt to find your Laserkraftwerk in the next room, along with a Gold Cane and other useful items.
Use your Laserkraftwerk to cut a hole in the thin metal just below the charge unit on the wall. Inside you should find several more useful items, including a Handgun. Use the button on the desk to release the door and then kill the three guards outside. Be sure to pick up the Marksman Rifle Upgrade: Laser before you continue on your way.
TIP:Your Assault Rifle contains a Laser attachment, so keep it charged and pay attention to your HUD.
Run towards the automatic doors. After seeing two Signal Detected notifications, it's time to stealth kill your way through. Sneak up behind the first guard on your left. If you're crouched, he won't see or hear you. Take him down and move around clockwise. Hide behind any cover and stealth kill the guards when their backs are turned. Finally, take the Commander down and focus on the bottom level. Go down and go through the same process again. This time, take the Commander out first, since he'll raise the alarm. After clearing the room, loot both levels.
The exit is on the top floor and clear of resistance for now. Go through two doors and go downstairs. Do not go through the automatic doors! Instead, go through the opening to your right. Crouch and crawl through, cutting through the metal sheets on the left side when they appear. You'll end up in the sleeping quarters for one of the two Commanders. Stealth kill him, but don't get spotted by the guard in the hallway. When the guard isn't looking, cross the hall and stealth kill the second Commander. Clear out the rest of the opposition using whatever method you'd like.
TIP:Cut through any available metal in each sleeping quarters, which lets you move around without alerting the guard.
Move around and climb into a pipe along the side of the wall. You'll see several guards below you. There are no Commanders, so take them out however you please. Loot the area when you finish. The next area has two more Commanders. They're hard to take out quietly, so get your Assault Rifle ready, just in case. If the final Commander is alerted he will hide in a back room. The exit is the ventilation shaft right behind him. After dispatching everyone, proceed to the exit. Drop through the floor and explore the area. Proceed through a round tunnel and into another square vent. Drop through another floor and venture into space.
You can only go one way, so head toward your objective. Take out the incoming drones with your Assault Rifle and jump to your objective with your floaty jump. Press a button to open the airlock chamber, then another one to move on to the Command Module. Remove your space suit and search for the Nuclear Keycode. The objective is marked on a scalpel beyond the first door. Watch the cutscene.
Once the cutscene is done, you'll have two Commanders to deal with. Prep your Assault Rifle, just in case, but make sure to avoid the giant robot patrolling the area.
Go down the hallway to the left of the robot and find the vent. Follow it until you pass over a very small catwalk, emerging at the base of a ladder. The Signal Detected prompt at the bottom of the screen will show the Commander closest to you. Climb a short way up the ladder but not to the top. Wait for the signal to get close to you and stop. Once it starts to move away again, climb up and stealth kill the Commander. Pick up the large gun in the middle of the catwalk and take out any opposition, especially the giant robot.
TIP:You can also stay on the ground level, hugging the left wall to end up at the base of some stairs. You'll have the opportunity to stealth your way through, but don't get caught, or you'll have to face the giant robot without your large gun.
Take the elevator at the far end of the room, which goes to the center of a small army of Nazi soldiers. Clear the area with your Assault Rifle. Work your way up, but keep an eye out for Kampfhunds lying around. The exit is near the top level, just off the ring near the edge of the room.
Go through the automatic doors and run to the end of the hall. Turn left, go upstairs, and then follow the catwalk to another set of stairs. Go down the stairs and turn left again. Go through some more automatic doors and follow the hallway until you find two soldiers. Take them both out and pick up the Nuclear Keycodes on the desk behind them.
Turn left and shoot the Kampfhund coming your way. Take out the soldier at the other end of the room and drop through the hatch near him. Drop down and move along the only path that's available, climbing into the pipe up ahead. Go up the ladder and eliminate the guards. Use your Laserkraftwerk to cut a hole through one of the panels and climb inside.
Take out the two guards in the next room and head downstairs to charge your Assault Rifle on the wall unit. Climb into the vent next to the charger and take out the guard by the escaltor. Head down and turn right to find some more soldiers. Use your Assault Rifle, since stealth killing will likely not work here.
Exit the car through the hatch in the floor and plow through the hallway guards with your Assault Rifle. Use the boxes for cover and proceed to another escalator. Kill the guards up top and move through the next door to end up back at the luggage area.
Return to the ship you arrived on, making sure to eliminate the giant robots in your path. Use the boxes for cover and hit them with your Laserkraftwerk. Take advantage of the charge unit along the wall. Get on the ship and turn right, opening the door to the cockpit to end the chapter.