Total Achievements: (18)
100% completion time: ~4-10 hours (Varies).

• Base Game: 2-4 hours per playthrough
  
• Expansion: ~40 minutes per playthrough

Difficulty modes:

• Normal
  
• Hard

New Game+: No
Missables: Yes
Mode: Single-player, horror

Achievement Types:
1) Story Related: (10)
2) Missable: (2)
3) Collectable: (1)

Expansion:
1) Story Related: (3)
2) Collectable: (2)

We will complete this game in achieving 100% by doing two walkthroughs on story mode and hard mode while the last playthroughs are three times on the Expansion. Follow what you like such as the hub area where you pick first where you want to clear but make sure to explore carefully as though there are not so hard to find collectables you need to be wary of conserving fuels despite having enough to later survive with no frustrations starting close to Act III. Do not worry about dying unless in hard, where you will respawn to the previous save. Dying in normal as an example during the Choir may have enemies despawn if you get killed by them.

You could speedrun the game technically under 1 hour but that might be pressuring you to not read the story so maybe 4 hours per playthrough is good enough I mean it's a story worth experiencing although for me I wrote the guide several hours and embracing the atmosphere not to mention some idling hours while pausing and working on my guide while watching the video down below. Justine on the other hand no matter what is under 40 minutes per playthrough. Hard Mode however should take less time because you already got most achievements on normal so only one remains for base game. By no means is my calculated time estimate accurate hence you could take 10 hours to 100% the game but at the same time not worrying about speedrunning time. Those are a different mindset to think about but at least better to add something.

This is a walkthrough guide also, all nooks and crannies. Thanks to all information shown in the past I was able to include miscellaneous items not related to achievements, the reason is the need to but I did not miss all items after all. If you wanna feel "safe" well this is it for you. In my opinion, this is why I can enjoy this game as I get immersed while working on this guide.

Tips:

• Lantern oil mentioned in the maps are all oil potions or oil barrels but the oil barrels are rare and will give a small oil to refill.
  
• You can juke the monsters like the Grunts but it's too risky and needs more space to maneuver.
  
• Progressing somehow to a new level sometimes gives you sanity to regain, this is fine on normal but enemies have increased speed.
  
• Try to exit out levels or if possible stay to the other side to trigger a despawn against monsters, ensuring this is a breeze through hard mode.
  
• Having enough fuel and tinderboxes even when you don't use them is better than less.

There are non-missables on story-related but there are numerous missables on collectables assuming you forgot to grab tinderboxes and notes as well as the endings. This is why you play normal mode otherwise hard mode reduces all tinderboxes you can grab.

As for Hard, you can only use 4 tinderboxes to save, optimising routes to follow and many more like save points is the best way to do which is why this is two playthroughs. Some areas can kill your sanity. I provided someone's video if you want to get this completed as early as possible at this point.

On the other hand, monsters will spawn and despawn after a certain amount of time has passed or if you die, what you also do is get items earlier so follow the numbered monster encounter plus re-entering areas will despawn monsters if you want it, mostly you hide also and they disappear.

The expansion is very straightforward only taking less than 1 hour but make sure to not miss those prisoners you will be interacting with, save or kill your choice. It has achievements so a good treat, especially that reference. There are no difficulty-related achievements for the Expansion so play normally and enjoy the short expansion.

There are a total of 151 tinderboxes and 49 notes according to the video. It is worth mentioning that you may explore a lot of times and get them well. However, you may not notice some right away so I want to put this spoiler guide for you to read. No, there is nothing related to collecting diaries (just collect them regardless don't worry about small details), metallic cylinders, oils, and laudanums to get the achievements, only the Diaries and Tinderboxes are related and will be needed but I included them here because they are there for various reasons. However, keep in mind we won't get all notes yet in the base game because only we get that on Expansion so it makes sense in that way.

I listed all areas here thanks to the video above. This may be as well a translated video-to-text guide. Additionally, all maps and images before the collectable is all from the wiki.
https://amnesia.fandom.com/wiki/Amnesia:_The_Dark_Descent

https://www.youtube.com/watch?v=RGhOXX7N69c

1) Rainy Hall, Old Archives, Entrance Hall
2) Tinderboxes: 29/151
3) Notes: 1/30
4) Diaries: 0/23
5) Metallic Containers: 0/5
6) Oils: 4/37
7) Landanums: 0/16
8) Achievements: 1/18
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Here is a safe but straightforward level but to get the idea of where to find.

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NOPE
Left when things were getting interesting in Amnesia: The Dark Descent.
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Achievement #1: Quit as soon as you enter control as Daniel, then you can go back to the game.



Old Archives is another one safe area but a place to grab your first Lantern for the entirety.



Entrance Hall is a safe hub, there are many areas to enter. They can be entered at any person's choices but for this order from the video we go from Archives > Wine Cellar > Laboratory = Refinery unlock.

1) Archives, Wine Cellar
2) Tinderboxes: 31/151
3) Notes: 5/30
4) Diaries: 3/23
5) Metallic Container: 0/5
6) Oil: 7/37
7) Landanum: 1/16
8) Achievements: 1/18
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As we begin with our first multiple section areas to enter, this is one to consider. Our goal is finding a key to the wine cellar.
Note: I added some icons so refer to my cropped images.



In here we need the ingredients to create a potion on the Laboratory.

1) Laboratory, Entrance Hall (Revisit)
2) Tinderboxes: 36/151
3) Notes: 7/30
4) Diaries: 3/23
5) Metallic Containers: 1/5
6) Oils: 10/37
7) Landanums: 1/16
8) Achievements: 2/18
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In here we make potions. We also find our first memory cylinder here which is not related to our achievements but better than nothing.



Now here I will mention about what you needed:

• Wine Cellar key (Found on Archives)
  
• 4 chemicals (Found on Wine Cellar)
  
• Potion of Acid (Made in Laboratory)

So now you have the potion of acid, go to the middle and obtain Alchemist achievement.

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Alchemist
Removed the Shadow's residue in the entrance hall in Amnesia: The Dark Descent.
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Achievement #2: Story Related. By this point you clear the Entrance Hall level. Doing this will regain your sanity. You can proceed to the next level which means you won't be here long (obviously).

1) Refinery, Cellar Archives, Archive Tunnels:
2) Tinderboxes: 45/151
3) Notes: 7/30
4) Diaries: 5/23
5) Metallic Containers: 1/5
6) Oils: 12/37
7) Laudanums: 3/16
8) Achievements: 3/18
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A somewhat safe but passable area, more tinderboxes too.



No notes and tinderboxes. a linear area but one laudanum is waiting.




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Escape Artist
Escaped the creature in the water in Amnesia: The Dark Descent.
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Achievement #3: Story Related. It's the chase from the same monster, run to reach either entrance to the Back Halls unlocking the achievement.

1) Back Hall, Guest Room, Study
2) Tinderboxes: 55/151
3) Notes: 11/30
4) Diaries: 8/23
5) Metallic Containers: 2/55
6) Oils: 15/37
7) Laudanums: 4/16
8) Achievements: 3/18
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1) Storage
2) Tinderboxes: 80/151
3) Notes: 13/30
4) Diaries: 8/23
5) Metallic Containers: 2/5
6) Oils: 18/37
7) Laudanums: 6/16
8) Achievements: 3/18
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After entering from Back Hall, this will be the first dangerous area (keep in mind for hardcore mode), so the Lantern is mostly used here and tinderboxes also. Special section for this 'cause it's my favourite of any levels in this game or because I run out of space in here but it will be a lot. Later, we will get to Act IV which is my favourite as well.

1) Machine Room, Back Halls (Revisit)
2) Tinderboxes: 85/151
3) Notes: 14/30
4) Diaries: 11/23
5) Metallic Containers: 2/5
6) Oils: 18/37
7) Laudanums: 6/16
8) Achievements: 4/18
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A safe area until you solve the puzzle. Make sure to collect collectables before doing the puzzle.


Go to the elevator as nothing much to do than progressing.

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Descendant
Taken a rough ride on an elevator in Amnesia: The Dark Descent.
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Achievement #4: Story Related. You can go straight to the next area by taking the 'stable' elevator, which means you get a nice achievement after a loading screen background appear.

1) Southern Block, Northern Block
2) Tinderboxes: 103/151
3) Notes: 14/30
4) Diaries: 14/23
5) Metallic Containers: 2/5
6) Oils: 25/37
7) Laudanums: 8/16
8) Achievements: 4/18
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This place is a labyrinth but the other will be so bear with me.



By far what I mentioned a labyrinth

1) Cistern Entrance, Control Room
2) Tinderboxes: 106/151
3) Notes: 15/30
4) Diaries: 14/23
5) Metallic Containers: 2/5
6) Oils: 26/37
7) Laudanums: 8/16
8) Achievements: 4/18
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Your third safe area hub. We need to go and drain the sewers as well as grab the vaccine for the fungi fumes but we must complete all three rooms.



This is by far the safest area.



(Only after solving the Control Room puzzle).

1) Cistern
2) Tinderboxes: 108/151
3) Notes: 15/30
4) Diaries: 17/23
5) Metallic Containers: 2/5
6) Oils: 28/37
7) Laudanums: 8/16
8) Achievements: 5/18
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Pipeworker
Lowered the water level in the cistern to reveal a new way out in Amnesia: The Dark
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Achievement #5: Story Related. Only inside this level would you get the achievement.

1) Morgue, Sewers
2) Tinderboxes: 112/151
3) Notes: 17/30
4) Diaries: 17/23
5) Metallic Containers: 3/5
6) Oils: 28/37
7) Laudanums: 12/16
8) Achievements: 5/18
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This is somewhat safe despite the Brute but nonetheless easy.



You should be done with this so moving on. The last area is where we need to go in order to reach the last remaining hub.

There is not a lot to find other than tinderboxes and laudanums.

1) Nave, Chancel
2) Tinderboxes: 126/151
3) Notes: 19/30
4) Diaries: 19/23
5) Metallic Containers: 4/5
6) Oils: 30/37
7) Laudanums: 13/16
8) Achievements: 5/18
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A final and fourth hub to relax on. On the other hand, there are two versions of both Nave and Chancel this is unmissable so follow the section walkthrough as you desire and once you progress without looking every nook and cranny you cannot get the previous collectables anymore once you reach the redux or II of the two locations you will not miss going.



This is by far my favourite area, also priority for collectables so we do it here first. We must go to this area first before other areas as I mentioned either II or redux because we cannot find exactly what is needed in here before moving forward story-wise after collecting all orb pieces.

1) Transept
2) Tinderboxes: 130/151
3) Notes: 20/30
4) Diaries: 19/23
5) Metallic Containers: 5/5
6) Oils: 31/37
7) Laudanums: 13/16
8) Achievements: 5/18
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A safe area before we go to the Choir. Each torture room reduces Daniel's sanity.

1) Choir - Entrance, Choir - Main Hall
2) Tinderboxes: 141/151
3) Notes: 20/30
4) Diaries: 20/23
5) Metallic Containers: 5/5
6) Oils: 33/37
7) Laudanums: 14/16
8) Achievements: 5/18
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Safe area before the Choir room.



Another largest area and second torture room, it's filled with Brutes around 6 so bear with this but it's the easiest map on hard also.

The strategy is to keep hugging the wall as much as you can, thanks to Yazite's way this should be a breeze. Also turn up gamma if you want to so you can see.
https://www.youtube.com/watch?v=jY35y1ijZD4

1) Cells
2) Tinderboxes: 144/151
3) Notes: 21/30
4) Diaries: 20/23
5) Oils: 35/37
6) Laudanums: 15/16
7) Achievements: 8/18
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This is a one-time area to explore before you get to the end for a reminder.


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Quitter
Failed to escape the cells and was consumed by the Shadow in Amnesia: The Dark Descent.
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Achievement #6: I think you can do this while inside the cell but either way you could do this when the Shadow appears ready to kill you, just go to it and instantly die.

1) Nave (Redux), Chancel (Redux)
2) Tinderboxes: 151/151
3) Notes: 21/30
4) Diaries: 22/23
5) Oils: 37/37
6) Laudanums: 16/16
7) Achievements: 8/18
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Nave but it's overtaken by the Shadow.



Same with the Nave II.


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Illuminatus
Picked up every tinderbox in Amnesia: The Dark Descent.
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Achievement #7: At the last tinderbox this unlocks the achievement immediately.


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Restorer
Collected the pieces of the orb and rebuilt it in Amnesia: The Dark Descent.
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Achievement #8: Story Related. Simply assemble all orbs before the final two levels progressing.

1) Inner Sanctum, Orb Chamber
2) Notes: 21/30
3) Diaries: 23/23
4) Achievements: 11/18
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NOTE: You need to get all of the notes in Justine as well. I will cover all of them in the different section.



Final area of this game, we can get different endings in here hence shorter completion.

Three endings will be in here but they are straightforward.

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Sacrifice
Allowed Alexander to escape in Amnesia: The Dark Descent.
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Achievement #9: Story Related. We simply wait without touching the pylons and then we get this achievement unlocked.

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Benefactor
Rescued Agrippa in Amnesia: The Dark Descent.
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Achievement #10: Story Related. Wait for the portal to open and then use the Agrippa head. If you also followed the walkthrough in here then we should have no problem doing this so achievement will unlock.

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Survivor
Killed Alexander and escaped the castle in Amnesia: The Dark Descent.
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Achievement #11: Story Related. Push and pull back the pylons which will take a smidgeful effort and then you get the achievement unlocked.

1) Complete Hard Mode
2) Notes: 21/30
3) Achievements: 12/18
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This is what you have been waiting for, honestly I think it should be less difficult to navigate now. I recommend this guy's videos and info on this guide here.
https://steamcommunity.com/sharedfiles/filedetails/?id=1524826424
Finding a good saving point or if you want to risk and save at the right spot then it's up to you.

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Masochist
My name is... Daniel... and I... have made life... exceptionally hard for myself.
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Achievement #12: Difficulty, Story Related. When you complete as usual after some saves and all that is then we get this achievement unlocked.

This video work wonders. Follow and you will succeed so 12 saves should be plentiful.

1) Cells, Library
2) Notes: 28/30
3) Achievements: 13/18
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To access this Expansion, we need to exit out Dark Descent and select the desktop launcher to select Justine, it will also allow you to use your existing save so we continue where we need to be. Unlike in Dark Descent we need to play the whole Expansion all over again for the endings.

This should not take long but I will still put on a how-to kill/save the hostages and also other miscellaneous etc. Only notes will be present in this game and we don't need tinderboxes we already did that but the Expansion is gonna take less than 40 minutes. This along with your current profile should be enough to get the last achievements.

The notes are also straight-forward to find here.

First area.



Second area.


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Still Alive
Became aware of the merits of A.S. Inc.'s Span-space Device in Amnesia: Justine.
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Achievement #13: Located on top of the bookshelf. This is an extra note.

1) Dungeon. Crypt
2) Notes: 30/30
3) Achievements: 18/18
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Third area.



Fourth and final area.


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Master Archivist
Read all notes in all games.
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Achievement #14: After collecting all 30 notes from Dark Descent and Justine, you should unlock the achievement.

Proceed until you get to the final room which of course you will see the achievement pop based on the choice you made against the Hostage Suitors. We must play the game 3 times.

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Egotist
Not a single victim survived in Amnesia: Justine.
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Achievement #15: Story Related. By following the short walkthrough I provided, you will get this achievement.

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Vacillator
Some victims died, some lived in Amnesia: Justine.
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Achievement #16: Story Related. Leave Victim #1 and #3 dead but #2 only alive. Alternatively, try leaving any two survivors alive either way.

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Altruist
Not a single victim died in Amnesia: Justine.
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Achievement #17: Story Related. It should be straight forward.

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Insanity
Achieved all other achievements.
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Achievement #18: Story Related. This is the last one, congrats in making this far and all 17 achievements you obtained will unlock this one.

Finally, a game I long to play since the release but only watched a lot of them. At last this is finished and I got to say I am very impressed and invested into the story because this is my cup of tea. The game was not that hard to 100% it only requires your game knowledge to do so and the Expansion was very short which I am glad so I can get this done. On the other hand, I spend a stupid amount of time writing this guide while watching few videos to get them all but at least the guide is finished.

The reason why this game has been stuck on my mind for good reasons is the atmosphere that is disturbing and immersive not to mention the fear of the unknown yet other horror titles I played have some ways to keep you going but not almost as memorable. No other games will keep me on hold due to how they might had used some tropes that is prevalent yet this game has the feeling of dread and curiosity after all the 19th century style was my favourite of the bunch unlike other well-known classic/modern horror where I laugh at them (Wow! What a Mansion) unless it's the other niche types, it was the best decision although I still feel dreaded but better late than never! This was my cup of tea ever since and I never stop thinking about it although it has some flaws the story experience will never be replicated like this the Lovecraftian horror is too mysterious.



100% finished, keep it up people and good luck :)

If you want to consider donating, I have the link here so you can send your money. Otherwise if not then that is fine, continue using this guide at your own benefit I won't ask too much.
https://www.buymeacoffee.com/Diviision

https://steamcommunity.com/sharedfiles/filedetails/?id=2957870846