Welcome to my guide, I'm gonna I'll help you attain every achievement in just one playthrough and will also feature every puzzle solution so you can easily check the guide and be done with them. The guide might look confusing and you might think it's not making any sense since you'll be solving the puzzles without looking their clues. Achievements are listed in order of unlocks, so if you missed an achievement you probably did something wrong!

The Guest has a terrible bug: If you open the steam overlay while zoomed in areas, the game will not work anymore and the only way to fix this is by restarting the game, so be sure to save once in a while in order to lose the least progress as possible.

Before we start, there are 2 achievements you will have to be careful since the beginning:

Life of the Others
Read all the newspapers.


I'd be safe and read every document, just check them for a second and (if possible) pick them up for the "Diogenes of Sinope" achievement, there's about 8 documents to read scattered through the game.

Diogenes of Sinope
Collect all possible objects.


You'll have to read every document and pick up every object you encounter, but these aren't hard to achieve, to be honest. Obviously you don't need to have them all on the inventory since you'll use a lot of them for puzzles, you just need to pick them up for it to register. Don't be too scared of this achievement, I even got it before picking up ALL of the items, Steam stats say you have to pick up 55 items, maybe they stack up in multiple loads! (They do! Thank you Storm_at_Sea!)

Bear in mind I'll have a counter for how many documents / letters / notes you have to read in each room for the "Life of the Others" achievement, these do not include notes that you can pick up! Only the notes that you can't!

Unless you complete the last puzzle in the game you'll be able to backtrack and read all the documents / pick up any missed items that you might have missed.

Let's move onto the game shall we?

First thing you want to do is go to the closet and input the code 503 on the toolbox locker.

The Prophet
Enter the toolbox password without combining the notes.


Now head to the telephone and type these numbers (note that 5 and 6 are switched), only input a new number when the phone isn't making any noise:
00-000
01-000
02-297
03-297
09-297
08-297
42-606
48-151 - This number unlocks the trapdoor on the next room, and it will unlock the achievement

Somebody there?
Call every single number on the phonebook.


List of items to look for the "Diogenes of Sinope" achievement:

• Cigarette (1/2 Total)
  
• Holy Bible
  
• Cigarette Box
  
• Travel Info (Suitcase Tag)
  
• Valve (1/3 Total)
  
• Boarding Pass
  
• Pencil
  
• Empty Lighter
  
• Envelope
  
• Piece of Paper x2 (Do NOT combine them before The Prophet achievement!)
  
• Door Knob
  
• Magazine (1/3 Total)
  
• Bulb
  
• Document (Power Supply Note)
  
• Screw Driver
  
• Hanger (1/3 Total)
  
• Battery [1V] (1/3 Total)

Number of documents that you need to read for the "Life of the Others" achievement: 3

Use the door knob and the screw driver on the door to proceed to The Bathroom

You'll have some sort of acid trip when entering the Bathroom, take the pills on the First Aid section. Try to use them again to unlock an achievement!

Overdose
Try consuming the bath pills again.


Here's the solution to one of the hardest puzzles in the game, just put the same symbols in the numbered order and then pick up the "Key R" item:


List of items for the "Diogenes of Sinope" achievement:

• Band Aid x2 (2/2 Total)
  
• Alcohol
  
• Soup
  
• Body Gel
  
• Shampoo
  
• Hanger x2 (3/3 Total)
  
• Pliers
  
• Straight Razor
  
• Battery [20V] (2/3 Total)
  
• Lockpick
  
• Key R

Documents that you need to read for the "Life of the Others" achievement: 3

Combine one of the hangers with the pliers to make a Lockpick and open the locked door. This will open the next room in the game which I'll call The Study, the entrance is in The Bedrooom

Upon entering the room you'll notice there's no power, it's time for another missable achievement, "The Maintenance Man"! After finding the power supply box and the last battery, insert the 3 batteries, now you have to solve this puzzle with just 2 movements.

First Move: Exchange right Battery 20V with right Battery 1V.
Second Movement: Exchange right Battery 5V with upper left Battery 1V


The Maintenance Man
Solve the batteries puzzle in just 2 movements.


Now that the power is back, you can scavenge for all the items in the room. After picking up the Sign ("Do Not Disturb") item, go to the door right next to the power supply and try to use the sign on the exit door:

Do not disturb
Use the sign and don't be disturbed.


While looking for items, below the vinyl player you can find a Ring and a Vinyl Disc, use the Vinyl on the record player:

Grasshopper & The Strangers
Listen to some music on the record player.


After finding the 2 remaining valves you can solve the next puzzle with a missable achievement, "Houdini", which you need to solve this puzzle with just 20 movements. All you need is 7! Put the 3 valves in their correct places in this puzzle:

Assuming you haven't turned any of the valves that should be the state of your puzzle.
Turn all the valves with clockwise movements!


Houdini
Complete the valves puzzle in less than 20 movements.


This puzzle unlocks the door to yet another puzzle:


Do what it's telling you to do and turn off ALL the lights including the ones in the Bedroom, Bathroom, and the whole Study!

Scared of the light
Turn off all the lights.


The solution to this puzzle is fairly simple, you can see the correct colors in this screenshot:


In order to progress you have to go back to the bedroom and call the number 01-138, this will initiate The Labyrinth section that also has a missable achievement properly named "The Labyrinth". You won't have access to any of your items in this section, and the solution to The Labyrinth is randomly generated, you'll have to do it through trial and error until you can load your savegame and get it on the first try.



You'll enter a labyrinth which you can choose from 2 door ways, one of these will let you progress, while the other door will reset the labyrinth to the first room (the one in the screenshot above). In case you progress you'll find a different room every time, just work your way through 3 doors, load your game and pick up your 4th final door, hoping it's the correct one. If it resets just load your save one final time and choose the other door in the end. Sadly I can't help much with randomly generated puzzles.

After seeing the door with the "We are Science" text in it, go around the area about 3-4 times to finally get access to the Strange Object item.

The Labyrinth
Complete the dream maze scene withouth failing.


You're finally back to the normal Study room, now combine the Strange Object with the 2 Rings you have found in this same room and put the Strange Object + Rings on the wooden base. Now you have to line up the object and the rings to create a figure presented in the chalkboard above you:



This will reveal a secret safe, the password is DYSTOPIA

Upon picking up the music box's Crank, use it on the music box and get your ears ready. This is yet another randomly generated puzzle, you have to input the melody in the right order to unlock the door to The Office. Save the game here just in case, and reload immediately in case you fail, if you can open the door on your first try you'll be rewarded with the "Wolfgang Amadeus Mozart" achievement!

Wolfgang Amadeus Mozart
Complete the music puzzle without failing.


List of items for the "Diogenes of Sinope" achievement:

• Ring x2 (2/2 Total)
  
• Battery [5V] (3/3 Total)
  
• Plate
  
• Vinyl
  
• Valve x2 (3/3 Total)
  
• Sign ("Do Not Disturb")
  
• Statue
  
• Silver Tray
  
• Document ("Oversight Instructions")
  
• Film
  
• Magazine (2/3 Total)
  
• Phone Book
  
• Cigarette (2/2 Total)
  
• Coaster
  
• Strange Object
  
• Handle (Music Box)

Number of documents to read in this room: 8

This is definitely the biggest room with the most puzzles in the game, the rest is gonna be a cakewalk from now on! Let's move into The Office

You're almost done! When you enter this new room another room which I'll call The Secret Room will open right in front of you, but we'll get there in a second. Upon entering The Office look for the Lighter Fluid. Combine it with the Lighter to have it working again! Now combine the working Lighter with a Cigarette and there you go!

Always the right time
Try lighting a cigarette.


Head over to the globe in this room, change the coordinates to 3ºN and 0ºW, you'll be in Madrid, Spain and will get another achievement:

Meet the devs
Locate the Team Gotham's headquarter.


Focus on the typewriter, use the "R Key" you picked up from the very first puzzle and write BENEFACTOR

Memoires
Write BENEFACTOR on the typing machine.


List of items for the "Diogenes of Sinope" achievement:

• Lighter Fluid
  
• Glasses
  
• Magazine (3/3 Total)
  
• Criptex

Number of documents to read in this room: 3

Let's finally go into The Secret Room and see what's in it!

New World
Get into the secret room.


There's not much to do in this room, use the ID Card you find here in the little slot below the desk, and input the password: 423

Supervisor
Type the password in the computer.


List of items for the "Diogenes of Sinope" achievement:

• ID Card
  
• Pen

Number of documents to read in this room: 3

I think there's no more documents to read from now on, so you should get the "Life of the Others" achievement now!

Life of the Others
Read all the newspapers.

The last puzzle of the game is in The Office, in a very small room, here's the solutions:


EXODUS: 5-8


ARRIVAL: 4-12

After entering this room you really can't go back anymore, the door will be locked and it's the final section of the game. Pick up the ID card next to the suit, it's the very last item to pick up!

Diogenes of Sinope
Collect all possible objects.


Now pray twice next to the bed in front of two screens to get one of the last achievements:

Always thankful
Be thankful twice.


To finish the game click on the button to get your dosage!

A New Beginning
Get to the end.


The last achievement is very easy. You don't have to idle 8 hours in-game thankfully! All you have to do it come back to The Guest 8 hours after taking the pill (finish the game) to take it again, just select Continue on the main menu and you'll be on the final room. Let's say you finished the game at 2PM, you'll be able to do this achievement at 10PM. At 10PM you can take another pill and you'll unlock the very last achievement, congratulations!

Waiting for the dose
Wait 8 hours and hit the button again.


Thank you so much for checking out the guide! I'd like to hear any feedback, if an achievement didn't work or if I missed something, any glitches or exploits are also helpful to add to the guide so share them on the comments! I hope I've helped you through The Guest!