The Dark Pictures Anthology: The Devil In Me

A video guide will almost certainly come along for this achievement eventually, but for those who prefer a text guide, see below. These are listed in chronological order and assume all characters are kept alive with one exception (Charlie needs to die in the incinerator by choosing the door instead of the grate). Some must be obtained in the standard/theatrical cut of the game, and some must be obtained in the Curator's cut. Note that unlike previous Dark Pictures games, progress toward these count across playthroughs, and you can use Scene Selection if needed to go back and get any that were missed. This guide will be updated with additional details and clarification, if needed.

THEATRICAL CUT:
1. & 2. Playing as Marie in the prologue chapter (The World's Fair Hotel), you'll meet your friendly host and then you'll be at the store counter with the choice to take the bath milk or the face powder. You must pick either one, and then replay the chapter and pick the other option to get credit for both items.
3. Playing as Erin in the Blackout chapter, you'll be trapped in a dark room with the killer. He will hold out the asthma inhaler and you'll have the option to Take or Attack. Choose Take (this is also the option that allows Erin to survive this scene).
4. Playing as Kate in the Wall chapter, you'll be holding an amethyst crystal in Kate's room. Mark will walk in and start a conversation. When a dialogue choice appears, choose "CURT - It makes me feel better" (heart option). When the conversation is over, walk to the desk and pick up the crystal.
5. Playing as Mark in the Workshop chapter, you'll be in a room with a vat of chemicals. (Be sure to successfully pass the button prompt to catch his camera as it falls.) Investigate the shelves in this area and you'll see one with cans of clearly-labeled paint thinner. Above the paint thinner is a new camera lens. Use Mark's stick thingy (down on D-pad) to reach it.
6. In the same section (playing as Mark in the workshop), you'll have to hide from the killer 3 times. Be sure not to fail any of the hiding or heartbeat events. After those are done, you'll see a workbench with a drill bit on it. Interact to turn into Frank West for a minute and attach the drill bit to the end of the stick thingy.
7. Playing as Jamie in the chapter Breathless, be sure to choose to save Erin over Kate in the suffocation chamber (don't worry, both characters will live if you choose Erin). Then, playing as Jamie in the chapter Interrogation, you'll come to a room with a red glow inside, which is the correct way to go to progress the story. Don't go into that room yet. Instead, go into the opposite room in the hallway, which is Jamie's room. Pick up the chapstick to the side of the bed.
8. Playing as Kate in the chapter Director's Suite, you'll be talking to Jamie about the screwdriver. When a dialogue choice appears, choose "NERVOUS - I need that." to take the screwdriver. (You also get the screwdriver with the other dialogue option, but this choice will allow Kate to live in the glass wall scene, even if Jamie pushes the button to reverse the direction.)
9. Charlie needs to have died in the incenerator for this next one, otherwise this scene does not appear. Playing as Mark in the chapter Cliffside, very shortly after the chapter starts you'll come to a small shack on the opposite side of a brick wall (before you go up the steps in the cliffside). The shack has a drawer that can be opened, and inside is another new camera lens.
10. Playing as Kate in the chapter Homestead, you'll be running through the woods with multiple fallen trees to either hop over or crawl under. Keep to the left and look for a crawl-under tree on the left, which will take you to a bridge you must shimmy across, and then a small shed. Run around to the left of the shed and pick up the key on the ground. Enter the shed using the key, and examine the body on the floor. Look to the left while examining the body to pick up the flashlight on the floor.
11. Playing as Erin in the chapter Lake, the police officer will arrive by boat and then be killed. You'll see his handgun (in this case, both his hand and his gun) lying on the dock. When a dialogue choice appears, choose "AUTHORITATIVE - Grab the gun!" The killer will prevent this, but Mark will instead grab the pepper spray which is what we need for this achievement.

CURATOR'S CUT:
12. & 13. Playing as Jeff in the prologue chapter (The World's Fair Hotel), you'll meet your friendly host and then you'll be at the store counter with the choice to take the pocketwatch or necklace. You must pick either one, and then replay the chapter and pick the other option to get credit for both items.
14. Playing as Jamie in the chapter Party, you'll come to a room with a closet you can open for a jump scare mannequin. After recovering, walk into the closet and pick up the Lounge key on the floor.