If you have a controller plugged in, the main menu may not function properly. You need to unplug it and use keyboard/mouse.

Get out of the room by pulling chair to the left wall where the open vent is, after getting to the next room you should see diary #1 (The Chief Diary #1) next to the table.
Crawl out through the door, go left past security camera #1, after it you will meet patrol robot #1, run from it and get into the first toilet room on the right side,pick up Che. Staff Cardkey in the last toilet cabin.
Get out of the toilet room and go into the opposite room (General Office - Bio. Zone), in there procced to the next room forward (General Office - Che. Zone), inside this room you will find diary #2 (The Chief Diary #3) in the far corner next to the bookcase and black sofa.
After picking up the diary go to the the hallway in between bookcase and lockers (small C-Lockers) and get to the only office with the lights on (Office #5).
Inside it you will find Diary #3 (A Certain Scientist Diary #1) behind the desk and Che. Office Locker Key on the shelf which you can get by pulling the chair.
From there go to the small C-Lockers and get Limited Access Area Cardkey 1 from the [C] 1-3 Locker.
Turn around and get out of the room through General Office Che. Zone Door into the corridor, on the left you will see Security Camera #2, turn right and go into the Meeting Room.
Make your way into the middle of the room and pick up Storage Locker Key.
Exit the room and go towards Security Camera #2. Before you go past the camera you need to get into Data Room. Be careful because the entrance to it is in the reach of the camera light.
Inside proceed to the room with PCs and interact with the only one that is on. You will get Diary #4 (A Certain Scientist Diary #2).
Get back to the corridor and go past Security Camera #2, after passing it you will get to the fork where you meet patrol robot #2.
Right Turn leads to the elevator (level exit) and Left Turn leads to other areas,where we will have to go for now to save our sister,so when patrol robot #2 goes to the right side,you should go left and proceed forward until you see the first door, it's another toilet room.
Get in and open the third cabin from the entrance and pick up Diary #5 (The Chief Diary #2) inside.
Get back to the corridor and go left towards the 2nd door on the right side (Storage Room).
Inside Storage Room pull chair to the left side of Big B-Lockers, get on the chair and interact with lockers to get Bio. Staff Cardkey.
After getting the card you need to go all the way back to the General Office - Bio. Zone (the first room you enter after getting Che. Staff Cardkey), when you get there you need to get in another hallway of offices and go all the way to the end to the Office #9.
Inside you will pick up Diary #6 (The Chief Diary #4) and Bio. Office Locker Key.
Get out of the Office #9 and go back to the beginning of the hallway, there you should find another set of small lockers (small B-lockers), get to the Locker 1-4 and get Floor Director Cardkey from it.
Go back to the corridor where Security Camera #2 is and go to the Floor Director Room.
Inside it on the shelf you should see Diary #7 (A Certain Scientist Diary #3).
Now go all the way to the Storage Room (left turn from where patrol robot #2 is),when you reach it don't go inside, instead proceed further into the corridor and enter Capture Room Area.
Inside Capture Room Area turn right and go until you reach Capture Room 1, go in and pick up Diary #8 (A Certain Scientist Diary #4).
Exit the room, turn right and go forward to the Capture Room 5, be careful of patrol robot #3, inside it on the right side you should see Diary #9 (The Chief Diary #5).
Eixt the room and wait for the patrol robot #3 to turn around (if needed) and follow it all the way to the end of corridor and get inside Capture Room 8, inside you should see last diary for Floor B3 - Diary #10 (The Chief Diary #6).
After getting last diary for this floor, get into Capture Room #9, save your sister by interacting with console on the left side and procced to the exit of the level (right turn where patrol robot #2 is).

Go forward from the beginning of the level,after leaving the room full of bookcases, look to your right and you should see Che. Staff Cardkey, pick it up,then go to the room on the left and interact with the only PC that is on.You should get Diary #11 (The Chief Diary #7).
Enter Data Room and turn right, then you will have to run from patrol robot #1 towards left side and hide from it inside the room which will be in the hallway on the left side.
In there you will find Diary #12 (The Chief Diary #8) on the desk.
Look Left from the diary you just picked and you should see Bio. Staff Cardkey.
Leave the room and go right, you should be able to see two doors after the opening on the left side, go into the 2nd one,but be careful of the patrol robot #2.
inside the toilet room open the last cabin and pick up Diary #13 (A Certain Scientist Diary #6).
Leave the toilet room and turn left to the fork which is guarded by patrol robot #3,
go to the left and get into Archive Room 1, inside this room pick up Book 2 on the table to your left,turn around and get into room with PCs, in this room pick up Book 1 which is on the first table on the left side, then get to the end of PC room and pick up Book 5 in the right corner behind the desk.
Get into the last room of archive area and pick up Book 4 from the ground (you should be able to see it as soon as you walk in), then go into the second opening in bookcases and pick up Book 3 from the shelf.
In this same opening put Book 5 into the open slot on the left bookcase.
Get into the last opening in between bookcases and fill in the rest of the spots:
Book 1 and Book 2 on the left side
Book 4 and Book 3 on the right side
Secret Room will be unlocked where you can interact with PC and rotate picture to get the passwords. Leave Archive Room 1 and turn right and go into unlabled room (Med Bay) which is protected by Security Camera #1.
After getting inside you will see Diary #14 (The Chief Diary #9).
Go to the left side of this room to the left of you on the floor next to the bed will be lying Storage Locker Key 1 pick it up.
Go to another door in this room (Research Room), look at the bed to your right and you should see Diary #15 (A Certain Scientist Diary #8).
Enter Research Room Room and enter passwords for the brains to unlock secret passage:
Enter secret room in the Research Area and interact with PC to your left to get PC Hint
and pick up Floor Director Cardkey in the far corner of the first room.
Get into the room in front of you and pick up Diary #16 (A Certain Scientist Diary #9) from the ground in the right corner of the room
and Diary #17 (The Chief Diary #10) from the bed in the left corner of the room.
Exit through Experiment Room 1 door, go forward to the left side (don't get caught by Security Camera) and enter Experiment Room 2.
Inside this room pick up Gate-A Keycard near the bed behind the curtains in front of you.
Pick up Diary #18 (A Certain Scientist Diary #10) in the far left corner of the room near cupboards.
Pick up Diary #19 (The Chief Diary #11) in the left side of the room behind the bed.
From Experiment Room 2 get all the way back to the toilet rooms, you need to get past patrol robot #2, but before getting all the way past patrol robot #2 get inside the first room to the right (Staff Room) and pick up Diary #20 (A Certain Scientist Diary #7) inside the room.
Robot will turn left when it needs to turn around, you can switch sisters by pressing Q, you can get past it like this:
After getting past patrol robot #2 you will get into area which is guarded by patrol robot #4, in this area you need to get into General Office - Che. Zone door, after entering it,go inside the first office to your left (Office #1) and interact with PC on the desk after moving chairs.
This will open Office #3 and Office #5 where you will need to hold buttons with both sisters at the same time.
After this go to the newly unlocked office (Office #7) and pick up Gate-b Cardkey.
Opposite to the Office #7 is located Office #8,enter it and pick up Diary #21 (The Chief Diary #12).
Exit Office #8, take left turn on the cross and go forward until you reach Office #4.
Pick up Diary #22 (A Certain Scientist Diary #11) from the desk and Storage Locker Key 2 from the floor.
Leave General Office - Che. Zone through the same door you entered and go left towards the gate while avoiding patrol robot #4.
After opening this gate go into the first door to your left (Floor Director Room), inside it turn left and interact with piece of paper on the table and then with PC, solve the puzzle if you want, then proceed to the next part of the room, enter password (8390) from PC into the safelock and pick up Limited Access Area Cardkey 3 from the safe.
Exit Floor Director Room , turn left and go all the way forward past Security Camera #2 until you run into Storage Room,get inside and open Locker A 3,2, you should get Diary #23 (A Certain Scientist Diary #12).
Now open Locker D 4,4 and take Diary #24 (A Certain Scientist Diary #5 ).

Exit Storage Room and go right,be careful not to run into zone of Security Camera #3.
Turn right again and go into the room, inside this room make your way towards Briefing Room door, in Briefing Room you need to make your way towards another Hold Button which will open secret passage in previous room.
Interact with PC in the secret room and enter the following password: 39785(this can be found by interacting with bookcases in the same room).
Pick up Limited Access Area Cardkey 2 from the corner where one of the bookcases just moved. Leave the room back to the corridor(Don't forget to grab your sister who held the button as she might be the one who doesn't have card to leave the Briefing Room and run forward past Security Camera #3 until you run into Monitoring Room door.
Enter it, interact with piece of paper on the table and pick up Unknown Key next to the screens.
Go to the Power Room (it's next to the Monitoring Room), open both power shields and set switches same way as on the screenshot. Interact with the button next to the power shield.
Go to the Monitoring Room and interact with PC there, switch to the other sister and go to the room that was opened in the same area and interact with another PC there. Input this password with both sisters at the same time: 19ae8h3sx7, this will move one of the bookcases in the room you are in. Go there and pick up Gate-C Keycard. Leave both rooms and exit through the door in the same area to the next level.

Go forward and enter the room on the left side, inside the room go left and get inside toilet cabin, pick up Diary #25 (A Certain Scientist Diary #14).
Make you way into the next room by crawling through the vent by using chair (it's on the left side behind the curtains on the screenshot)
Once inside next room go to the left and pick up screwdriver from the ground.
Then pull the chair to the vent (it's next to the jammed door) and interact with it to open,proceed to the next room through the vent.
Once in the next room make your way out of it through the door and go into hallway.
Turn to the right leads to the Reception Zone (we'll go there later), go forward and take the first turn left and go to the 2nd room on the left side (Room B-4). Inside this room go to the right side and pick up Diary #26 (A Certain Scientist Diary #13) next to the bed.
Right opposite to this diary is another toilet cabin, go inside and pick up Diary #27 (The Chief Diary # 13) that is hidden behind curtains.
Now go to the Reception Zone, as soon as you enter it, go left and pick up Diary #28 (The Chief Diary #14) from the desk and Room 11 Cardkey from the ground.
From the reception desk go forward and take first turn right which leads to the toilet rooms, inside the first toilet room you should find Diary #29 (The Chief Diary #15) lying on the ground.
Exit toilet room,go back to Reception Zone and take the second turn to the right, go forward past Power Room (we'll get there later) and enter big room.
In this area you need to do the following:
1) Go to the room 11: Pick up Room 18 Cardkey from the bed, pick up piece of paper with word "Gyro" written on it from the table and pick up Room 2 Cardkey.
2)Go to the room 2 and place your sister on Hold button in there.
3)Go to Room 18 and interact with Hold button in there.
4)Go to Room 10.
Refer to this badly drawn map.
Once in Room 10 pick up Diary #30 (The Chief Diary #16) from the floor behind the curtains.
Then go next to the desk chair and pick up Unknown Key, it's not higlighted with flash as other objects but you should see [E] Pick up when you get close.
From this room go back to Power Room that you passed earlier. Once inside look to your left and pick up Diary #31 (The Chief Diary #17).
Now go to the this power shield,open it and activate middle switch my by pressing enter.
This will open Secret Room next to Power Room, go in there.
The First Room Puzzle Solution:

After this make one of the sisters to hold the button to open the door.
The Second Room Puzzle Solution:

Take Unknown Keycard, Red Book, A note from Jack from safe.
Make your way out of the Secret Room and go to the big area to your right, go to the exit of this area and take left turn.
Go forward past fire exit until you see two toilet rooms, go into the first one and pick up Diary #32 (A Certain Scientist Diary #15).
Exit out of the toilet room, go further: left of you you will see lasers and the only way now is turn right, go in there but be careful not to run into vision area of security camera. Proceed further and you run into another area with rooms.
Go straight forward into the Room 06 and pick up Green Book from the bed on the right side.
Exit out of Room 06 go forward then turn left and go into Room 08. Inside this room pick up
Diary #33 (A Certain Scientist Diary #16) next to the desk.
Turn right and pick up Orange Book from the bed.
Go out of the Room 08, turn left and go into Room 09 and pick up Yellow Book from the desk.
Leave Room 09, turn right and go till the end to the Room 15, make your way to the bookcase and place books like this:
Get into the secret room that was opened next to you and enter this password: 211869.This will open two new secret rooms: one in the lobby before security camera and one opposite to Room 08.

For the following puzzles, you need to have one sister in each puzzle room. You'll be solving puzzles in each room so the other sister can proceed further into their room.

Solution to the Lobby Room 1 Puzzle:
Solution to Room 08-1 Puzzle:

Solution to the Lobby Room 2 Puzzle:
Solution to Room 08-2 Puzzle:

Solution to the Lobby Room 3 Puzzle:

Solution to Room 08-3 Puzzle:
Let your other sister into next puzzle by holding the button room before reverting everything like on the last screenshot. Both blue and green lasers need to be solved here to open the exit.
Solution to the Lobby Room 4 Puzzle:
Solution to the Room 08-4 Puzzle:
Press the button,switch to another sister and pick the last diary - Diary #34 (A Certain Scientist Diary #17).
Solution for rest of the puzzle:

Now make your way into the lobby with both sisters while avoiding guards and escape through White Doors!( by pressing E on different sides of the doors with each sister).

Guide was made by IGGYTRIX.
Special Thanks to alphabetsoup for figuring out Double PC puzzle and testing the optimization of the guide.
Don't forget to like the guide and if you feel like you want to support me more, you can reward this guide using the steam points or reward me on profile directly.
If you found any mistakes or typos - let me know in the comment section.
If you want to use this guide on your website, don't forget to credit the creator.
Have a good achievement hunt!