Here's a basic walkthrough based on what I recall of my playthrough.
Go to your room (walk through the only door you can access and then through the door directly opposite it).
The code is 1234
Get your gear from your room
Go to the cryo laboratory. Take the Stellara gallery photo and read the 'big toy' email to get the code for Amelia Kindhart's room.
The code is 2701.
Enter the vent that is hidden behind the glowing crates.
Exit the dining room and head back toward your apartment. Look for Amelia's room not far from yours.
Entering the code for her room will allow you to unlock a cutscene, but there's nothing else in there.
Continue down the hallway and down the ramp. Enter the Cargo Archive. Turn on the breaker in there.
Go around the walkway in the next room (Warehouse 2) to get the Lian gallery photo.
Walk into the room called Front Ramp.
Straight ahead is a control room. Walk past the room and look through the window. You will see the combination for the door (9047).
Pick up the forklift key.
Raise the forklift load up so you can jump across the walkways in the Front Ramp.
You can go up to the upper control room if you like, but it just tells you about the galley picture that you should have seen when you walked down the ramp.
Jump across and go into the vent, drop down, save your progress at the computer, and continue into the nearby room. Turn on the breaker and climb up into the vent above you.
The Astra gallery photo is found by following the first path to the left in the duct. If you miss it and fall through instead, it's no big deal. You can get it later.
When you wake up, go through the door into another set of bunks, then through another door into yet another set of bunks. There is a Hira gallery photo to you right as you enter the second room. There is a vent directly ahead of you. Take it through to another room. There is a computer there is some lore on it. Go into the other vent.
Follow all the left turns to arrive in another room. Get the omnitool and the Siren-12 gallery image and turn on the circuit breaker before returning to the duct. Take left turns again and you should find a long passage. the duct to the right near the end has yellow on the cover, allowing you to open it with your omnitool.
Go to the map, then left, through the animal stasis lab, and down toward the workshops. Hop the crates, crawl through the broken door, and continue through the vent to the next room.
Get the gun, get the key, read the hint, and grab the Vectra gallery photo before continuing through the door, using the 234450 code found on the Vectra photo.
Go down the ramp and duck under it to enter another vent.
Turn on the circuit breaker and go through two doors. Turn on the circuit breaker near the flesh wall and enter Warehouse 1.
Shoot the fuse to open the emergency hatch, pick up the batteries for your pistol, and continue through the hatch.
Note the vent in the next room. Walk in between the boxes to find a way up to the top, then hop over to the vent.
Follow the left wall of the vent to the end, where you will find two fork trucks with lighted displays.
Go into the control room and shoot the fuse, opening the room beneath it. Go down the ramp and follow the yellow railing (on the side near the control room) until you find the room beneath it, containing the fork truck key.
Raise both fork trucks. Use the one furthest from the exit vent to get the Yunsi gallery photo, then use the other one to reenter the vent and leave the room; you have what you need. Follow the right wall of the vent to get out.
Go back through the emergency door and activate the fork truck in the first workshop. crawl under it and go right to get a Lyra gallery photo, then turn around.
Follow the disgusting vent to the end, where you will conclude this version (there is a Chroma gallery hoto in the bathroom).
Note: For all you completionists out there, I was unable to find all 12 of the gallery photos. My playthrough found 9.
