I didn't receive this despite the fact I played on a completely fresh save without ever pressing the Tab key or middle click whilst in-game. I'm assuming doing so in the menu may override receiving this achievement too. For the love of god, unless you want to potentially do multiple playthroughs of this game, disable your Tab key on your keyboard or remove it entirely and keep your fingers off the middle-mouse button, even in the final sequence of the game where you can speed up/slow down the game speed.

Just talk to the two scientists in the corner of the lobby of the university until their dialogue is exhausted. You may have to examine the portrait next to them with left and/or right-click too.

Look at the painting in the university's library, and then examine ALL of the shelves.

Examine everything in the crime scene: the hole in the wall, the bed, the bar, the window, the bucket, the corpses, the desk. If I've left anything out, please let me know.

Test tube on broomstick handle. Insert into hole in wall WITHOUT rubbing it on the rug first.

Before doing the next achievement, turn off the lamp and close the blinds in your office.

Follow the Armitage dialogue until you fail, then the Lone Carter dialogue until you fail, then the John Smith dialogue until you succeed.

Talk to all the inmates in the loony bin on your very first visit.

Exhaust all dialogue with the archivist and examine every option on the shelves.

Do the next achievement at night. DO NOT RETRIEVE THE SHOVEL IN THE TOOLBOX AT DAY.

Save before attempting this. If you've played Oblivion or ESO, then this should be a piece of piss for you.

Examine all of the graves with LEFT click.

There should be a guide on how to complete this properly on Steam somewhere. IF YOU MESS UP, A PREVIOUS SAVE WON'T HELP YOU, YOU HAVE TO RESTART THE ENTIRE GAME.

ONLY EVER USE YOUR FATHER'S AMULET ON THE OIL LAMP

Save your game at Akeley's house. Enter any concoction of the chemicals into Akeley. Reload, then create the correct concotion (a guide of which should be on Steam somewhere).

IDK yet, it's either one of the first two choices. "My motives are my own" isn't correct.

When you play as Lovecraft himself, save the game. Immediately interact with the globe and ONLY press on the buttons on America, France, and Arabia. Reload the game, find Lovecraft's grandfather's journal, read it, then do the same as before.

I received this achievement upon looking at the two corpses in Antarctica. I assume to complete this achievement you have to talk to certain NPCs (including the ones in the loony bin) and examine all the graves in the graveyard which have some backer names on them. Just talk to everyone you come across and examine all the graves and you should be fine.

Use the undiluted, raw magic dust on the all of the selectable parts of the right corpse in Antarctica until you get this achievement.

Give the raw, undiluted laxatives to the guard in front of the tent BEFORE diluting it.

Button order is: right, right, right, left, middle, left.

In one of the buildings in the underground city, there should be a sharp looking rock on the floor. Pick it up, return to the cocoons, and rescue your friends.

Story dependant.

Also story dependent, but it requires sitting through and watching the entire credits before it will unlock. (thanks to MrEniena for pointing this out)

I only got two deaths and didn't achieve this. First death is getting caught in Innsmouth, second is getting shot in the underground city by the purple robed dudes.

User secret6 adds:
1. Two death in the beginning of the game on road to railway station from two different zombies
2. Got "Master cheater" achievement. After getting game restarts from the beginning, so i think it counts as death.
3. In the underground city i didnt interact with panels with my tentacle. So after entering code of door it didn't open and seems it was counted as death
4. I've been caught and shot by cultists In the underground city
5. On the last screen of game when you dressed as cultist you are asked by other cultists where you go. i replyed "not your business" ans was killed

I assume you need to show the letter to the bookstore owner next to your office BEFORE you show the detective at the crime scene.