Lobby

Exit the bunker on the moon's surface and follow the coned path to another bunker.

Inside, use the airlock terminal: press the button, then use your Interface Module to scan the security monitor.

Enter the elevator and press the up arrow to reach the botany lab.

Go to the Main Wing door and use your security access to enter.

Enter the room with the sprouting body and locate the Founders' Office door (it's broken).

Take a right to the Laboratory 01 door and use your Interface Module to unlock it.

Inside Lab 01, listen to the voice recording, read the terminal's emails and diary, then crawl through the vent behind the terminal (CTRL).

In the vent, follow the single path to a water cistern area. Go right around the corner and save at the Wireless Access Point.

Crawl underneath the gap in the door to the right of the Access Point.

In this room, locate the keycard on the table with the name 'Maria' and note its number (e.g., 9785).

Go to the terminal marked 'Maria's' and enter the noted code. Press the 'EXE' option.

Follow the cables through the now-open door.

Go around the curtained area, past the Lab 02 room, and into the dark hallway.

At the end of the hallway, crawl into another vent.

Crawl straight forward and follow the narrow hallway until you find the vent exit on your left. Crawl through to enter the chemical lab. Save at the access point above the hatch.

Mix the disinfectant: use the terminal and select 'Isopropyl Alcohol' for Base, 'Copper Ions' for Active 01, 'Hydrogen Peroxide' for Active 02, and 'EDTA' for Stabilizer. Press 'TEST'.

Backtrack to the lobby area where you first entered.

Enter the decontamination chamber; the disinfectant will be applied, and the doors will open.

Inside, look at the keycard on the floor beside the body (William's keycard) and note its ID number (e.g., 4619).

Go back to the area where the Access Override terminal was (near Maria's terminal).

On the terminal, enter William's noted code (e.g., 4619). The gate to your right will open.

Climb down the ladder, follow the hallway, and climb down a second ladder.

Navigate the dark area by following the red pipes and objects on the ceiling: out the doorway, right along skinny red pipes, left, straight up a slope, to a dead end, left through a doorway, follow red hanging crates, turn right at a wall to a larger red pipe, then left along the large red pipe to the crank wheel.

Approach the crankwheel and press E/M1 to turn it.

Make your way back through the tunnels to the ladder, following the red objects on the ceiling.

Climb up the ladder. Run to the cafeteria area and crawl under the door to reach the cistern. Save here.

Climb down the ladder in the cistern. Follow the lit tunnel and climb up another ladder.

Follow the tunnel to a vent door and crawl through to the office. Save at the access point.

On the terminal, enter William's code (4619).

Go to the 'SECURITY' tab and upgrade your Interface Module by scanning the screen.

Make your way back to the lobby area, get in the elevator, go up, and use the airlock to head back to the Moon's surface.

Get back to the other bunker and use the airlock again to re-enter the building. This will transition you to Chapter 6.