This guide should cover all achievements in detail, with the exception of some of the "examine every item"-type, which don't list every individual item, though I've given as much helpful information as I can for those. If there are any errors or if you'd like something added, please contact me.

A helpful note: Most of the achievements can be collected over multiple playthroughs- so if you don't collect every trophy item or document or examine every object the first time, you don't need to get them all on your next playthrough, only the ones you missed. The major exception to this is the Perfectionist achievement.

Out of Body Experience
Experience the first ending.


When you find Dr. Faust in the final area, don't drink the D'versahe in the bowl next to him. Instead, continue forward and solve the final puzzle (using the drawing from the big stone with the button to align the pillars correctly and release the golem) and examine the huge glowing thing past the vine-choked tunnel to get this ending.

Earthly Minds over Delicate Souls
Experience the second ending.


When you find Dr. Faust in the final area, just drink the D'versahe from the bowl next to him to get this ending. It's the brown bowl on the ground just to the right of him.

Glutton for Punishment
Die in five different ways.


1. Poison Plants
Use an axe to repeatedly cut at the blue poisonous vines, rather than getting them to retreat by shining light on them. After enough cuts, you'll black out and get a game over screen. There are many opportunities to do this throughout the game, starting with the very first time you encounter the plants, after getting off the Link Elevator beneath the base and picking up the first axe you find.

2. Submarine Crash
When you're in control of the submarine, just smash it into some walls at full speed. The first few times will crack the glass, the final time will sink the sub and lead to a game over screen as you drown.

3. Crystal Talisman Runs Out of Energy
In the ruins after the submarine ride, you'll eventually pick up a portable crystal talisman that you can charge at the glowing blue obelisks and equip to make the poisonous vines retreat. However, the talisman runs out of energy over time, fading from blue to red. Just stand in the middle of the vines after they've withdrawn until the talisman runs out of energy and turns red, and the vines will close in and strangle you, giving you a game over screen. Again, there are many opportunities to do this throughout the game, starting with the vines behind the vertical metal stand you set the talisman into shortly after picking it up.

4. Caught by Lizard Mummy
When the lizard mummies in the connecting halls are revived and give chase, just let them catch you right away. This one doesn't lead to a game over screen, but just reloads you right before the mummies are revived.

5. Caught by Shoggoth
In the desert ruins of Rub'al Khali, on your way out after solving the constellation puzzle and discovering the Jurassic-era map, your character will hear a rumbling and warn that he needs to get out of there. If you don't run to the exit, the Shoggoth (which looks like a big black blob with some glowing yellow nodules) will bear down on you and kill you. As with the mummies, this leads to an automatic reload rather than a game over screen.

After all of the above, the achievement still won't register until you beat the game, and possibly only with Ending #2 (drinking the D'versahe). I'm not sure if that's because Ending #2 counts as a death and one of the above methods doesn't, or just because it doesn't tally them until the end regardless of which ending you get- and now that I've gotten the achievement I can't test to find out.

Death-defying
Finish the game without dying.


Basically, do the complete opposite of Glutton for Punishment, above. Don't die by any of those methods, and choose Ending #1 (Out of Body Experience) just to be on the safe side. See the achievement below for more specific info on avoiding the mummies.

Note that several moments in the game might seem like possible deaths, but are just part of the normal game progression- these include getting sprayed by the plant in the bio lab and the glowing vines that wrap around you after the bit with the cat, getting attacked by the tentacles while in the submarine, getting caught by the mummies at the very end of the escape sequence (if you did it right, you'll make a comment about it all being in your head instead of restarting), and falling into a hole while running from the Shoggoth in the desert ruins. These can all be safely ignored.

Escape Artist
Don't get caught by the mummies in the Connection halls.


This is extremely misleading, because you DO get caught by the mummies, unavoidably. It's more like "don't get caught by the mummies until the right moment". Also, the game seems to be a bit strict about this one- I saved just before the event and redid it several times, but it still counted me as having gotten caught. Maybe loading from an earlier save would work, but still, be careful to get it right the first time if possible!

In the ruins after you take the elevator down from solving the symbol drawing puzzle, there's an area where you pass through a narrow hallway with red lizard mummies on either side, and come to a path with three forks- the middle one leads through another, circular chamber with a few mummies, and the other two go around either side of that chamber. All three paths connect at the end and lead through a tunnel that ends in a bas relief room and an orb that you have to turn to activate the obelisks in that area.

After you turn the orb and head back, Frank will get a headache and say he can't bear the pain any more. When you get to the narrow hallway again a black mist will block your path and a glowing phantom will appear and bring two of the lizard mummies to life, which then begin to chase you. It's possible to run ahead and then duck behind some stones and sneak away, but much easier and faster to simply run down one of the two outer forks, look back to make sure both mummies are following you, then run down the other outer fork, making a big loop and getting back to the narrow hallway before they can catch you. As you dash through the hallway other mummies will spring to life; keep going through the next room and you'll find the entrance blocked by that same black mist. At this point you have nowhere to go and the mummies will catch you, but instead of dying and reloading just before the phantom appeared, Frank will comment about it being a hallucination and walking out of the room should get you the achievement.

Important: Don't just rush through the loop as fast as you can, or you might find the second mummy waiting for you at the other end. Make sure both mummies are following you down the same path before completing your run. And no matter what you do, DO NOT take the center fork- the phantom will appear in the circular chamber in the middle to revive the mummies there, and Frank will slow down so much during the scene that the first pair of mummies can catch up to him.

Cryptographer
Solve the radio room puzzle.


Huh? What radio room puzzle? Turns out there is one, but it only appears after you have your first mansion flashback beneath the base, triggered by touching the green Elder Thing statue in the locked room in the Bio Lab. Once you wake up from that, go back up the elevator to the base and return to the radio room, and this time the radio will be on and you can interact with it. But first listen to the noises coming from it. Every so often, you'll hear a short burst of Morse Code (you may have to adjust the volume knob first), which you can translate using the chart on the bulletin board nearby. If you're having trouble, here's the solution: The code spells out "MF 2 5". So press the MF button on the radio, set the SEL1 knob to 2, and the SEL2 knob to 5. For me, this worked right away, if it didn't for you, try adjusting the Tuner knob.

Sharp as a Tack
Solve the symbol drawing puzzle at the first try.


This one's pretty easy- just make a save before attempting the puzzle, and reload if you screw it up at all. The only difficult part is knowing that it matters which direction you draw the lines in, something the symbol drawing you get doesn't make obvious. Draw the Z-shape starting from the top, the vertical line to the right also starting from the top, and the diagonal line below starting from the bottom.

Paying Close Attention
Solve the puzzle on the cellar door without any clues.


I'm not sure how paying close attention equates to being psychic, but anyway: when you have your last journey to the mansion after tapping Dr. Faust on the shoulder deep in the ruins (right after where you can pick up the sacrificial dagger trophy item), be very careful not to examine the calendar on his desk, and just to be on the safe side, none of the masks or other exhibit items either. The calendar gives some numbers, which correspond to the exhibit numbers and gives you hints as to how to unlock the cellar door. The correct combination is just what it looks like on the achievement icon- the dot within a circle, then the crescent moon, then the sun. Note that before you can solve it you need to find the missing lock piece, which is beneath the floorboards in the room with the star projector. The floorboards can be pried up with the crowbar that's on a table at the bottom of the stairs.

Private Investigator
Find all documents in the game.


There are a total of 25 documents in the game. You can check how many you have at any time by opening your journal.

In Upuaut Base (before taking the first elevator down): 10
1. Dr. De Witte's medical records 1- on the desk in the room where you begin the game.
2. Radio officer Hansen's journal 1- in a drawer in the radio room.
3. Radio officer Hansen's journal 2- in a drawer in the first room on the left in the crew rooms.
4. Dr. James Barlow's journal 2- hidden behind the boxes on the wall shelf in the second room on the left, in the crew rooms.
5. Ferguson's note on his dreams- on the shelving in the second room on the right in the crew rooms.
6. Location of the Upuaut Antarctic Base- on the bulletin board in M.C. Blake's room.
7. Dr. Faust's note about the purpose of the expedition- atop a small pile of books on the shelving beneath the bulletin board in M.C. Blake's room.
8. Dr. James Barlow's journal 1- on the bottom shelf of the book case next to the desk in M.C. Blake's room (a bit hard to see).
9. Note about my momentary death and suspension- in the wastebasket next to the fridge in the infirmary. You may have to duck to pick it up.
10. Dr. De Witte's medical records 2- in a desk drawer in the infirmary.

In basement of Upuaut Base (before taking the second elevator down): 4
11. A note on degrading mental stability- in a cardboard box on the floor between the depot and bio lab hallways. Hard to spot.
12. A note about the nature of the sessions- on the left desk in the bio lab.
13. Anonymous note- on the corpse in the room with the frozen Elder Things.
14. Dr. J. Barlow's note on the D'versahe mixture- in the bottom cabinet of the bookshelf in the locked room of the bio lab.

Ruins 1 (before getting in submarine): 5
15. Poisonous Plants and the Dangers of Cutting Them- under the axe you find right after stepping off the Link Elevator into the subterranean ruins.
16. Dr. Blake's notes on the initial discoveries 1- in a cardboard box next to a flashlight and axe, right near the relief with the line of gold lizard men.
17. About the climate of the caverns- inside the tent just before the submarine.
18. About the nature of underwater caverns- inside the tent just before the submarine.
19. Dr. Blake's notes on the initial discoveries 2- inside the tent just before the submarine.

Ruins 2 (before solving symbol puzzle to activate elevator): 1
20. Dr. Faust's note on the stopping of my heart- in the bottom cabinet of the book case in Dr. Faust's room before waking from the submarine crash.

Ruins 3 and Faust's Mansion (before picking up disc that transports you to desert ruins): 5
21. Dr. Faust's journal entry 1- on the chair next to the bed where you first awaken in Faust's mansion.
22. Letter about Necromantic means of data inquiry- inside a drawer in the table in Dr. Faust's office in the mansion, on your left as you enter. Frank comments that this is the same room he saw in an earlier vision.
23. The Place Buried Under the Sands in the Arabian Desert- in the top left drawer of the dresser in the mansion room with the star projector.
24. Dr. Faust's journal entry 2- on top of the desk in the mansion room with the star projector.
25. Dr. Faust's journal entry 3- on top of a crate next to a lantern in the basement of the mansion, near the puzzle door.

Super Sleuth
Get all secrets in the game.


There are 10 secrets, but only 7 create journal entries. Discovering a secret will make a message and a star icon appear in the corner of the screen briefly.

In Upuaut Base (before taking the first elevator down): 3
1. Radio Officer Hansen's carvings- appears automatically after reading Hansen's journal 1 and 2 and examining the wooden statue in his locker.
2. A note on the dual personality problem- in Johan De Witte's locker. The key is in a drawer in the second room on the left in the crew rooms.
3. The self-operating machine I've found in Dr. Blake's room- activate and speak with the robotic head in M.C. Blake's room. To solve: Switch on the machine with the blinking red lights. Set the dial on the oscilloscope to 2 and fiddle with the slider bar until the first green light is activated, then set the dial to 4 and fine-tune the slider again. Once both lights are green, hit the switch that's blinking yellow on the metal case.

In basement of Upuaut Base (before taking the second elevator down): 1
4. Strange message from VHF radio- solve the radio puzzle. Requires backtracking up to the Upuaut base after the first mansion flashback in the locked room in the bio lab. See the Cryptographer achievement for details.

Ruins 1 (before getting in submarine): 1
5. Pine Cone Chamber- across from the room where you find the five glyph stones is a breakable wall. Smash it down and enter to get the secret (though it won't show up in your journal). It's the same room that has the pine cone trophy item.

Ruins 2 (before solving symbol puzzle to activate elevator): 2
6. Elder Stone Chamber- shortly after waking from the submarine crash, you'll find an area that looks like an altar across from a black mirror. To the right of this area is a breakable wall. Enter to get this secret (no journal entry). The Elder Stone trophy item is behind this wall as well.
7. The dot glowing a different colour- after placing the orange crystal and activating the star map, examine the one star that's large and glowing bright orange to get this secret.

Ruins 3 and Faust's Mansion (before picking up disc that transports you to desert ruins): 3
8. Reptilian Mask Chamber- Shortly after leaving the elevator, there's a room with three columns and some stairs going up. Across from the stairs is a breakable wall that leads to a secret mummy crypt (no journal entry). The Reptilian Mask trophy item is in there too.
9. A letter about the polishing of the initial Conarium- in the mansion, there's a letter inside a wooden box that's perched on top of the bookcase to the right in the star projector room, but you can't get it until you get the metal lock piece hidden under the floorboards. After leaving the room with the lock piece, you'll hear a loud thump. Go back into the room and the box will now be on the floor where you can reach it.
10. Star map projected onto the ceiling of the library room- activate the star projector in the mansion. To do this, you'll need to get the disc with the starfish shape on it from the sub-basement (it's in a small box along with a phonograph cylinder), then go back up the ladder and plug it into the base of the projector before pulling the lever to activate it. Examine the star map on the ceiling to get the secret.

Impressionist
Get all notebook drawings in the game.


There are only 4, and all are clues to solve critical puzzles, so this shouldn't be too hard.

Ruins 1 (before getting in submarine): 1
1. Five glyphs- on the central island across from the huge revolving sphere door. Used to solve the puzzle to open said door.

Ruins 2 (before solving symbol puzzle to activate elevator): 1
2. A diagram consisting of several symbols- in the star map chamber after placing the orange crystal. Needed to solve the symbol puzzle.

Desert Ruins and Final Area: 2
3. Circular stone tablet with lots of inscriptions on it- examine the stone tablet right in front of you as soon as you appear in the desert ruins.
4. I've found some symbols, carved on a rock plate- after encountering Dr. Faust, continue to the area with the last puzzle and press the button in the middle of the large standing stone. Frank will copy down the stone's etchings.

Trophy Hunter
Get all trophy items in the game.


There are 20 trophy items total. You can check how many you have and examine them by hitting left ctrl from your inventory screen.

In Upuaut Base (before taking the first elevator down): 3
1. A book titled At the Mountains of Madness- in the locked room in the shed where you restore the power. The key is in the first aid cabinet next to the generator.
2. Upuaut Expedition Sketch Book Vol. 1- in a drawer in the first room on the right in the crew quarters.
3. World's History and Myths- In the cabinet in the top of the book case next to the desk in M.C. Blake's room.

In basement of Upuaut Base (before taking the second elevator down): 3
4. Octopian Statue- in a wooden crate in the Depot hallway.
5. A book titled Timebore- during the mansion flashback after touching the green Elder Thing statue, there's a crate with a lantern on top of it in a hallway. Approach it from the other side to find the book inside.
6. Upuaut Expedition Sketch Book Vol. 2- in the top cabinet of the bookcase in the locked room of the bio lab.

Ruins 1 (before getting in submarine): 3
7. Object with Pinecone in the Centre- across from the room where you find the five glyph stones is a breakable wall. Smash it down with your axe to find this.
8. Elder Sign Tablet- inside the rightmost sarcophagus on the right side of the central island across from the enormous revolving sphere door.
9. Cryptic Statue- behind the tent just before the submarine are five standing stones with holes in them. The statue is tucked into a hole on the rightmost stone.

Ruins 2 (before solving symbol puzzle to activate elevator): 3
10. Phonograph Cylinder with a Song- playing in Dr. Faust's room before waking up from the submarine crash. Just pick it up off the phonograph.
11. Elder Stone- shortly after waking from the submarine crash, you'll find an area that looks like an altar across from a black mirror. To the right of this area is a series of two breakable walls concealing this item.
12. Feathered Mask- Slightly before the room containing the first lizard mummy you see, one of the hallways has small paths to the right and left. Following the right path leads to a dead end with a skeleton wearing this mask.

Ruins 3 and Faust's Mansion (before picking up disc that transports you to desert ruins): 6
13. Reptilian Mask- Shortly after leaving the elevator, there's a room with three columns and some stairs going up. Across from the stairs is a breakable wall that leads to a secret mummy crypt. The mask is at the far end on a small altar.
14. An Ancient Wind Instrument- in the room with the metallic Elder Thing statue surrounded by lizard man worshipers, this item is lying on the floor up the stairs to the left.
15. Sacrificial Dagger- just before the ruins begin to turn into Faust's mansion, there's a side area surrounded by bells. The dagger is on an altar and appears right after a vision of lizard men gathered there.
16. Emperor Penguin Figurine- in the right side of the large cabinet in Dr. Faust's office in the mansion. Frank comments that it's the same room he saw in his earlier vision.
17. Curious Wooden Mask- in the rightmost crate in front of the ladder leading down to the mansion's sub-basement.
18. A mystery novel called Darkness Within- this is right in front of the mirror across from the bed in the room where you first awaken in the mansion, but it will only appear after you've explored the sub-basement area. After you've examined and taken everything but before going into the locked room with the stone disc, backtrack up the ladder and back to the top floor to get the item.

Desert Ruins and Final Area: 2
19. Elder Thing Statue- after smashing the wall describing the black protoplasm in the desert ruins, take the first left you can. There's a small dead end and the statue is at the foot of the top coffin on the left.
20. Necronomicon- after encountering Dr. Faust, explore the shoreline of the island behind him. The book is near the water a little ways from the right side of the bridge leading to the last area.

Perfectionist
Finish the game with 100% progress.


Unlike many of the other achievements, this one needs to all be done in one playthrough. However, it doesn't require you to do absolutely everything. To get 100% progress, you only need to:

Find all 25 documents
Witness all 18 memories
Find all 7 secrets (apparently the only secrets it counts are the ones that create journal entries)
Get all 20 trophy items (which means you'll be getting the other 3 unmarked secrets anyway on your way to some of them)

The only tricky part here is the memories, as it's not entirely clear what the game counts as a memory. Mostly it means the parts where Frank gets a headache and sees a blue figure of an expedition member talking about the ruins, but it may also include visions of the lizard people, and possibly even the times the glowing, tentacled phantom creature appears. However, this is easier than it sounds. There's only a couple memories that you're at all likely to miss if you're going through the game thoroughly, the rest should be simple to find if you're not skipping any areas.

The first one that's possible to overlook is a vision of the lizard statue you find shortly after entering the ruins for the first time. It's in a big circular chamber surrounded by alcoves containing altars, and looks like a sitting humanoid shape with a lizard head and an eye in the palm of its hand. There's also some wooden scaffolding next to it. If you walk up to it you should see a vision of the same statue with its head toppled onto the ground next to it.

The second one, and the one most likely to be missed, is right in front of the very first lizard mummy you see, near the end of the section of ruins between the submarine crash and solving the symbol puzzle. This section contains a room with lots of orange crystals, one of which you can take and use to activate the star map that gives you the symbol you need to activate the elevator. DO NOT solve that puzzle as soon as possible (and to be safe, don't even take the orange crystal yet). Walk right past the orange crystal room and when you reach the mummy you should trigger a memory of Dr. Faust talking about how some mummies were put in coffins but others were put into alcoves and stuck in with some kind of weird goo. This is the one that's easy to miss.

After this you can do the orange crystal puzzle, and when you pass by the mummy a second time you should see a vision of a glowing phantom bringing the mummy to life, after which Frank discovers that he's bleeding.

Here's a quick checklist of the other requirements. See their respective achievements for more details on their exact locations.

Documents:
In Upuaut Base (before taking the first elevator down): 10
1. Dr. De Witte's medical records 1
2. Radio officer Hansen's journal 1
3. Radio officer Hansen's journal 2
4. Dr. James Barlow's journal 2
5. Ferguson's note on his dreams
6. Location of the Upuaut Antarctic Base
7. Dr. Faust's note about the purpose of the expedition
8. Dr. James Barlow's journal 1
9. Note about my momentary death and suspension
10. Dr. De Witte's medical records 2

In basement of Upuaut Base (before taking the second elevator down): 4
11. A note on degrading mental stability
12. A note about the nature of the sessions
13. Anonymous note
14. Dr. J. Barlow's note on the D'versahe mixture

Ruins 1 (before getting in submarine): 5
15. Poisonous Plants and the Dangers of Cutting Them
16. Dr. Blake's notes on the initial discoveries 1
17. About the climate of the caverns
18. About the nature of underwater caverns
19. Dr. Blake's notes on the initial discoveries 2

Ruins 2 (before solving symbol puzzle to activate elevator): 1
20. Dr. Faust's note on the stopping of my heart

Ruins 3 and Faust's Mansion (before picking up disc that transports you to desert ruins): 5
21. Dr. Faust's journal entry 1
22. Letter about Necromantic means of data inquiry
23. The Place Buried Under the Sands in the Arabian Desert
24. Dr. Faust's journal entry 2
25. Dr. Faust's journal entry 3

Secrets:
In Upuaut Base (before taking the first elevator down): 3
1. Radio Officer Hansen's carvings
2. A note on the dual personality problem
3. The self-operating machine I've found in Dr. Blake's room

In basement of Upuaut Base (before taking the second elevator down): 1
4. Strange message from VHF radio

Ruins 2 (before solving symbol puzzle to activate elevator): 1
5. The dot glowing a different colour

Ruins 3 and Faust's Mansion (before picking up disc that transports you to desert ruins): 2
6. A letter about the polishing of the initial Conarium
7. Star map projected onto the ceiling of the library room

Trophy Items:
In Upuaut Base (before taking the first elevator down): 3
1. A book titled At the Mountains of Madness
2. Upuaut Expedition Sketch Book Vol. 1
3. World's History and Myths

In basement of Upuaut Base (before taking the second elevator down): 3
4. Octopian Statue
5. A book titled Timebore
6. Upuaut Expedition Sketch Book Vol. 2

Ruins 1 (before getting in submarine): 3
7. Object with Pinecone in the Centre
8. Elder Sign Tablet
9. Cryptic Statue

Ruins 2 (before solving symbol puzzle to activate elevator): 3
10. Phonograph Cylinder with a Song
11. Elder Stone
12. Feathered Mask

Ruins 3 and Faust's Mansion (before picking up disc that transports you to desert ruins): 6
13. Reptilian Mask
14. An Ancient Wind Instrument
15. Sacrificial Dagger
16. Emperor Penguin Figurine
17. Curious Wooden Mask
18. A mystery novel called Darkness Within

Desert Ruins and Final Area: 2
19. Elder Thing Statue
20. Necronomicon

Nosy Parker
Examine all objects in the game.


Unfortunately, I can't provide a complete list- I'm not even sure exactly what counts as an object and what doesn't. Just try to explore thoroughly and pick up everything you can, like clocks, tools, sculptures, etc., and eventually you'll get it, as it doesn't all have to be in one playthrough. Make sure to check drawers and cabinets too. One commonly-missed item is the Elder Thing statue that triggers your first Mansion flashback in the locked room in the bio lab- after you wake up from that sequence you can pick the statue up and examine it. That was the item that finally made the achievement appear for me.

Bookwurm
Check all the books in the basement and mansion.


I can't provide a full list for these either, but it's not too hard to get- just be thorough and pick up and read every book you can during the game. There actually aren't all that many, and if I remember correctly I got this during the short dream sequence right after the submarine ride, when you can explore a couple rooms from the base, one of which was previously locked. Also, trophy item books do not count towards this achievement.

Grand Inquisitor
Examine all the notes and diagrams in the game.


Again, not entirely sure what does and doesn't count for this, but I got it on my first run and it wasn't too difficult. Just keep an eye out for things posted on walls and bulletin boards, like the photos and notes next to the door to the radio room and in the bio lab. As long as you're careful in the base and mansion areas you should be fine, as none of them are concealed or anything.

Masquerade
Check all the wooden masks in the mansion.


Just examine all the masks during your final trip to the mansion near the end of the game. They're hard to miss, really. However, this may prevent you from getting the Paying Close Attention achievement on the same playthrough, as some of the masks are clues for solving that puzzle.

Wireless Operator
Use the walkietalkie voluntarily, in every location that it is available.


Pretty simple- every time you move to a new area (by which it means an area that requires loading before you can continue the game), use your walkie-talkie from the inventory screen.

What are you doing out there?
Walk out of opposite sides of the map outside the base.


When you first step outside the base into the snow to go fix the power generator, walk as far as you can forward away from the base, then do the same thing, but trying to go the other direction, behind the base. Each time you'll be stopped with Frank saying it wouldn't be wise to wander too far.

Sparky
Provide electricity to the base.


Bellhop
Manage to run the Link Elevator.


Deep Dive
Get on the submarine.


Carved Catacombs
Reach the Connection halls.


Demons of the Past
Reach the Mansion for the second time.


Under the Sands
Reach the ruins under Rub'al Khali.


Almost There
Reach the final level.


These are all unlocked just by progressing through the game, and can't be missed.