Return of the Obra Dinn

I recommend doing this as a separate (partial) playthrough after you earn the 14 achievements related to completing chapters, solving X amount of fates, and completely solving the book.

There are 60 crew members in the game. As the achievement name states, you are going to have to blame every single death (with the exception of crew members #4 - Martin Perrott the Third Mate, and #28 Fillip Dahl the Captain's Steward) on the Captain. While going for this achievement, you will not be able to earn the Obra-Done achievement as that requires you to fully solve the book, which means you would need to get everything correct.

Note: In order to be able to point out the cause of death for crew members, you will first have to unblur their faces. This game mechanic is pretty simple. If a face in the crew portrait is blurry then the appropriate information to solve who they are hasn't been presented to you yet. If the face looks clear, then at some point in a memory you have viewed you were given the information to figure out who they are. In order to blame all deaths on the Captain, you are first going to have to progress through the game until you unblur every face. This can simply be done by viewing every memory, most of which are presented to you in a linear manner. When you have seen everything in Chapters 1-7, 9, and 10 (Chapter 8 is a special chapter that won't be seen while going for this achievement, but also isn't necessary), all faces will be unblurred and you can continue.

The goal is to get every crew members death wrong here since this achievement requires you to (wrongfully) blame the entire crew's demise solely on the Captain. Be careful not to get any death correct by accident as it will void the achievement. For that reason, I advise saying that the Captain (#1 - Robert Witterel) killed himself by hanging himself with a noose, and the remaining crew members (excluding the two exceptions noted above) were all "axed" by Captain Witterel. The reason I used these choices is because

The achievement will pop just after boarding the rowboat you arrived on after the man who rowed you to the Obra Dinn informs you of a storm coming. After waiting a few seconds, the game will fade to black, you will be briefed on what happens a few weeks later, and you will be 50 Gamerscore richer!

BONUS! You will also earn the Abandon Ship achievement shortly afterwards when your maid delivers you a letter in the middle of the night. This is for getting the "bad" ending of the game for not correctly solving everybody's fate. You probably noticed along the way to this achievement that Chapter 8 was never explored. That can only be viewed if you have everything correct before boarding the rowboat.

EDIT: I've been informed by user BiLLzuMaNaTi that you don't even need to accurately identify the crew members to their faces in the picture. This will save some time towards going for this achievement! Just blaming their cause of death on the captain will suffice.

In this video I walk you through the game to get all the achievements in one playthrough

Achievement Walkthrough: