I couldn't find an achievement guide for this game so i went and made one myself ( ͡° ͜ʖ ͡ °) I tried to make this guide as spoiler-free as possible: achievement descriptions that reveal story elements were removed, and all spoilers (which are mostly bosses' names) are hidden under the <spoiler> tag.

If somebody decides to revive Pascal's Wager wiki - feel free to copy information from this guide. This, however, does not apply to professional websites who steal entire steam guides and monetize them. You people suck.

There are five sets of achievements in the game, tied to the main campaign and downloadable content.

• Main campaign - the main storymode of the game.
  
• Tides of Oblivion (ToO) - a story DLC which is integrated into the main campaign.
  
• Deep into the Dark Mist (DitDM) - a roguelite boss rush DLC which is integrated into the main campaign.
  
• Obsession Challenge - a standalone challenge mode.
  
• Dance of the Throne (DotT) - a standalone story DLC campaign.

All DLC achievements are listed in their resp. categories.


Yes, in the main campaign some achievements cannot be obtained on casual difficulty, and standalone DLCs have achievements tied to different difficulties.


5 playthroughs of the main campaign.

• One achievement requires beating NG+3/Journey 4 under a certain condition.
  
• One more requires to beat the game without leveling up (Altar Lv1).

2 playthroughs of the Dance of the Throne DLC.

• There are two achievements that require to beat the DLC on hard difficulty, which isn’t available on the first playthrough.

2-3 “playthroughs” of the Obsession Challenge.

• There are two non-stacking achievements for beating story bosses on different difficulties, as well as an achievement for no-hitting all story bosses, which is easiest to achieve on the lowest custom difficulty.

https://steamproxy.com/sharedfiles/filedetails/?id=2979421455
https://steamproxy.com/sharedfiles/filedetails/?id=2985693762
https://steamproxy.com/sharedfiles/filedetails/?id=2984877031
https://steamproxy.com/sharedfiles/filedetails/?id=2977187090
https://steamproxy.com/sharedfiles/filedetails/?id=3020348536

Achievements for the main campaign are separated into several categories:

★ Journey 1 - list of achievements that can be obtained in one run, including mutually exclusive achievements which require savefile backups to get.

• Story achievements - unlock automatically as you progress through the game.
  
• Missable achievements
  
• ToO achievements - DLC achievements; 1 is missable.
  
• DitDM achievements - DLC achievements; none are missable.
  
• Misc. achievements - can be obtained at any point of the game.
  
• Endings achievements - endings requirements and resp.achievements.

★ Subsequent Playthroughs - list of achievements that require two or more playthroughs to get.


Specifically:

• All story achievements
  
• The Truth
  
• Challenge
  
• Legendary Courier

If you switch difficulty from normal to casual mid-game, you won't be able to switch back.

If you want to lower difficulty without consequences then get the Egg of the Bearer from a statue in Heggem's mine - it halves damage dealt to you and can be picked up and returned repeatedly at any point of the game.

◌ The only achievement that is affected by the Egg is Legendary Courier - you have to beat NG+3 / Journey 4 without using the Egg. Using it during the first three playthroughs is completely safe.
◌ Using the Egg does not prevent you from getting different endings.


Pascal's Wager has 3 manual save slots and an autosave slot. The game autosaves all the time, and manual saving requires to rest at an Altar. Exiting the game without interacting with an Altar will not overwrite your manual save slot. Manual saves can be copied/backed up in the Load Game menu.


No spoilers - when you're about to hit one the game will graciously warn you and give you a prompt asking if you're ready to proceed. My advice is to take those points of no return seriously and to backup your savefile before proceeding. You might be in for a nasty surprise if you turn out to be unprepared - underleveled, or lacking resources. Remember that lowering difficulty is a permanent action that locks you out of certain achievements.

And do not neglect Terrence's upgrades. Other playable characters might be more to your liking, but Terrence is the protagonist. Not upgrading him will come back to bite you.

These achievements get automatically unlocked as you progress through the game and can be ignored.
◌ These achievements cannot be obtained on Casual difficulty.


Crazy Prologue





Father and Daughter





Wedding under the Moon





The banality of evil





Deicide





Demiurge's Destruction





The Apostasy





The Cultists





My love

Most of missable achievements require to perform multiple actions throughout the game. All of them (except Whisper of the Heart) can be obtained in NG+ / Journey 2 and onward if you failed to get them on the first playthrough.


Nightmare
Defeat a Strong Obsession during Lunatic


To get this achievement let your sanity drop to 0 in a boss fight, then defeat the boss.


The Truth
Kill all Strong Obsessions during Lunatic


Awarded for killing all chapter bosses in the Lunatic state in one playthrough: Maddened Ascetic, Holy Father, Jenny of Exilium, Fused Sprenger, Edith, Proxy Higgins, Usurper, The First Messenger
The achievement gets unlocked when you defeat the final boss.
◌ Cannot be obtained on Casual difficulty.


Heavy Armed
Acquire the Dazzling Melos Bottle


Awarded for upgrading a Trophy called Pitch-Black Melos Bottle 7 times. Сrafting material required to upgrade Melos Bottle (called Condensation Honey) drops from chapter bosses only when they're killed in the Lunatic state.
◌ For more detailed information on Melos Bottle check chapter 3 of Trophy guide.


Witness
Finish all the Tales


Awarded for completing all sidequests (except for ones from the Tides of Oblivion DLC) in one playthrough. Check Tales + Contracts guide for the full list and walkthroughs.


Whisper of the Heart
Complete all companion' contracts in a new game round


Awarded for completing Viola, Benita, and Norwood's sidequests in the same playthrough. Check Tales + Contracts guide.
◌ Companions' contracts themselves have no time limit, but their progress carries over to NG+, so this achievement might be exclusive to Journey 1.


Death Knell



Granted for helping Elena in Edith.
◌ This achievement and Escape from Madness are mutually exclusive. If you want to unlock both in one playthrough then copy your savefile in the main menu before speaking to Frollo at the 3rd Belltower. To get this achievement, stick to your agreement with Elena.


Escape from Madness



Granted for helping Frollo in Edith.
◌ This achievement and Death Knell are mutually exclusive. If you want to unlock both in one playthrough then copy your savefile in the main menu before speaking to Frollo at the 3rd Belltower. To get this achievement, choose to support Frollo, and then visit the divine courtroom.

Tides of Oblivion is a story DLC which is integrated into the main game. 2 story achievements are unmissable; 1 achievement is missable; the rest can be obtained at any time.

To access the DLC:
◌ After defeating Katib chapter boss, Fused Sprenger, speak to Jerold and agree to help him.
◌ After defeating Edith chapter boss, Edith, a new area gets unlocked - a (previously flooded) seashore. If you agreed to help Jerold in Katib then you will find his ship there.

In Journey 2 and onward the icon for the DLC area appears in the top right corner of the map after you complete Edith.

Puppet of Hatred


Story achievement.


The Hero Who Went Astray


Story achievement.


The Answer



Ending achievement. See resp. chapter of the guide for the list of requirements to unlock it.


The Foreign Swordsman
Activate every max talent of Jerold


Missable. Awarded for fully upgrading Jerold's talents tree. For this you will need 19 Sea Tooth Bones and 5 Immundus Diamonds. Check out this guide if you need help finding upgrade materials.
◌ If you'd rather save Diamonds for other characters then backup your savefile before spending them on Jerold and reload after unlocking the achievement.


The River Shall Flow



Awarded for completing a sidequest "River of Memories". See Tales + Contracts guide for the walkthrough.


A Lad from the Depth



Awarded for completing an unmarked sidequest which becomes available after you complete "River of Memories". See Tales + Contracts guide for the walkthrough.


Dominator's Revelry



Awarded for feeding five Ichthyosaurian Heggies.
◌ Purple Heggies hate Bone Fragments.
◌ Blue Heggies hate Anthozoan Bones.
◌ Golden Heggies hate Health Potions.
If you accidentally pissed off a Heggie it will be back after you rest at an Altar.

[1] can be found in the village, by following a secret path on the left side of this bridge.


[2] is in the Scavengers' Lair. After defeating the boss ride the elevator down, throw a switch that rotates gates, then ride the elevator back up and backtrack into the lair. You will find a new passage that was previously locked. The Heggie is inside.


[3] is in the pond in front of the Tower of the Origin.


[4] is in the snowfields. Take the path on the left. When you reach an area where Scavengers are fighting Sludge Collectors look for a Collector who's chilling on a ledge, surrounded by two torches. Behind him is a platform you can jump down to. Go around and climb back up, then exit the building and turn left. The Heggie is behind a corner.


[5] after completing sidequest "River of Memories" return to the village, you will find the Heggie on the previously inaccessible shipwreck.

◌ This Golden Heggie appears to hate Sanity.


Trading Without Borders
Find all the Siflers in Ichthyosauria


Awarded for finding 4 Ichthyosaurian Siflers.

[1] The first Sifler is on the ground floor of the first village, behind a circular elevator.


[2] The Sifler is right past the grand bridge that connects the Corpse Pit to the Scavengers' Lair.


[3] On the left side of the exit from the Scavengers’ Lair is a small building with an elevator inside which leads to the Caverns. You will find the third Sifler there.


[4] In the snowfields go past the fountain to reach a large wooden walkway. It's goes over the street on the right side of the fountain.

◌ Cross the walkway; walk past another wooden walkway, towards a bridge marked by two torches; you will see a Scavenger fighting a Sludge Collector. Past them are two ladders - one leads up, and the other leads down. Pick the one that leads down.

◌ From there it's one path with a bunch of short dead ends here and there. Past a shortcut that leads back to the street you will find another ladder which leads to the last Sifler. Not far from the 4th Sifler is an entrance to the Treasury.



Beg, Borrow or Steal



Awarded for defeating an optional boss Treasure Thieves who can be found in the Treasury.
◌ Feed Ichthyosaurian Heggies to obtain 5 stones from them.
◌ To find the Treasury see directions for finding the 4th Ichthyosaurian Sifler, the entrance is not far from him.
◌ Pick up "Treasury Master's Trial" at the doors to the Treasury and use it to insert the stones. The order is Treasury -> Heggie -> Humans -> Siflers -> Colossus.


Pieces of Old Days
Discover the ancient memories buried deep in Ichthyosauria


Awarded for finding all 28 documents scattered across Ichthyosauria. See Documents guide for the full list and locations.

Deep into the Dark Mist is a rogue-lite boss rush mode which is integrated into the main campaign. None of the achievements are missable.

◌ To be able to enter the Dark Mist you need to purchase Dim Mist Lamp from Glenn which becomes available after you complete Katib. Mist Camp can be accessed from any location by walking towards a map's edge, indicated by a bell post that is used to summon Glenn's carriage. Unlocking next zones requires Oil which becomes available for purchase after you complete more story chapters.

◌ DitDM trophies are strongest in the game and are pretty much mandatory for subsequent playthroughs and the Obsession Challenge. See chapter 4 of my Trophy Guide for the list & how to obtain them.

◌ Benita performs great in the Dark Mist. Her life steal lets you save up healing flasks, and her projectile/spell parry has an incredibly generous window and can parry nearly anything.

◌ Normally when you die to a boss in this mode you get kicked back to the Mist Camp and have to start from scratch, but here's a tip: the game autosaves at the start of each Terror Obsession battle, so when you're about to die you can safely quit to the main menu, and on reload you will be back to the start of the bossfight ( ͡~ ͜ʖ ͡°)

◌ Using the Egg of the Bearer does not disable the achievements tied to the dlc.

Dark Mist Drifter
Defeat all the Terror Obsessions in the Dark Mist Border

Explore the Dark Mist Border to raise Obsession meter, and defeat all bosses.


Dark Mist Explorer
Defeat all the Terror Obsessions in the Dark Mist Interior

Same as above.


Dark Mist Voyager
Defeat all the Terror Obsessions in the Dark Mist Depths

Same as above.


Dark Mist Warden
Defeat all the Terror Obsessions in the Dark Mist Cave

Same as above.


Dark Mist Lord
Defeat the powerful Obsession at the end of the Dark Mist


After defeating all bosses of the Dark Mist Cave you’ll get an option to fight a secret boss. This achievement is awarded for defeating it.

These achievements have no time limit and can be obtained at any point. Some of them you will unlock naturally as you progress through the game, others require some work.


Ascetic
Get killed for 50 times

Self explanatory.


Alchemy Apprentice
Use the Altar for Alchemy

Awarded for crafting a potion for the first time.


Druggist
Make 80 potions

Awared for crafting 80 potions. Combat items do not count.


Victory
Blessed by Benita

Awarded when Benita successfully blesses a potion for the first time.


Merchant in the War
Make 30 Weapon items

Awared for crafting 30 Combat Items.


Blacksmith
Acquire 20 Trophy items

Awared for crafting 20 Trophies. Can be 20 copies of the same Trophy.


Ingenuity
Acquire 3 Trophies with +5 quality

Upgrade 3 Trophies to +5.


Great Master
Acquire 6 Trophies with +5 quality

Upgrade 6 Trophies to +5.


Beginner
Inset an immundus

Awarded for upgrading a talent for the first time.


Grandmaster
Insert 5 Immundus Diamonds

Awarded for using 5 Immundus Diamonds to upgrade talents.


Loss of Sanity
Have a mental Lunatic

Awarded when your sanity drops to 0 for the first time.


Crazy
Accumulate 5 hours of Abnormal


Awarded for playing in the Abnormal state for 5 hours. You will most likely unlock this achievement while grinding for Anthozoan Bones.


Illusion
Acquire 1000 anthozoan bones


Awarded when you gather a total of 1000 Anthozoan Bones - luckily, you can spend bones whenever you want, you don't need to have all of them on you. Anthozoan Bones drop only when your character is in the Abnormal state, so equip Melos Bottle and grind. Check chapter 3 of Trophy Guide for information on Melos Bottle and best places to farm the bones.


Chivalry


Awarded for completing sidequest "Headless Knight". See Tales + Contracts Guide.


War and Destiny



Awarded for completing three sidequests - "Headless Knight", "Old Man and the Candle", and "Die or Become the Sendril" - in one playthrough. See Tales + Contracts Guide.


Blood Ties
Complete Viola's story


Awarded for completing Viola's contracts. See Tales + Contracts Guide.
◌ The achievement gets unlocked upon speaking to Viola after defeating Karst Cave chapter boss.


Hand in Coffin
Complete Norwood's story


Awarded for completing Norwood's contracts. See Tales + Contracts Guide.
◌ The achievement gets unlocked upon speaking to Norwood after defeating Karst Cave chapter boss.


Redemption
Complete Benita's story


Awarded for completing Benita's contracts. See Tales + Contracts Guide.
◌ The achievement gets unlocked upon speaking to Benita after defeating Karst Cave chapter boss.

Alchemist
Get all Alchemy formulas


Awarded for collecting all crafting recipes.

• Recovery
  
  • Elixir of Recovery - reward for completing Benita's 3rd contract
    
  • Elixir of Energy - reward for completing Benita's 2nd contract
    
  • Elixir of Stamina - Sifler (Katib)
    
  • Elixir of Hallucination – defeat the boss in Adamina, then shank the old woman next to a cauldron
    
  • Elixir of Sanity - Witch's Note (Heggem)
    
  • Elixir of Health - Witch's Note (Heggem)
• Enchancement
  
  • Elixir of Epiphany – have Benita bless an Elixir of Epiphany*
    
  • Petrification Powder – have Benita bless a Petrification Powder*
    
  • Potion of Wealth - reward for completing Benita's 1st contract
    
  • Anti-Sendril Elixir - complete sidequest "Die or Become the Sendril", then bring the note that you get to the old man in Edith
    
  • Dimming Elixir - Sifler (Katib)
    
  • Brute Force - Sifler (Exilium)
    
  • Powder of Defence - Sifler (Heggem)
    
  • Elixir of Intertia - Sifler (Adamina)
    
  • Antitoxin Potion - Sifler (Exilium)
• Combat Item
  
  • Soul River Water - ToO recipe, given by Bravo (not required for the achievement)
    
  • Blinding Smoke - Sifler (Edith)
    
  • Stun Crystal - Sifler (Katib)
    
  • Poison Awl - Sifler (Exilium)
    
  • Wildfire - Sifler (Adamina)

* Successfully blessing Elixir of Epiphany and Petrification Powder by Benita has a chance to unlock their formulas. Upgrade her Talent which increases blessing chance to 100%, then backup your savefile and start blessing.


Wisdom
Find all Documents


Awarded for collecting all documents in the game except for those from the Tides of Oblivion DLC. See Documents Guide for the full list and their locations.


Hide and Seek
Find all Siflers


Awarded for finding all Siflers in the game.

Heggem (2)
◌ 1st Sifler is at the end of the bridge.
◌ 2nd Sifler is next to the second Altar.


Adamina (1)
◌ The only Sifler is on a broken bridge that can be reached by dropping down from a ledge above, not far from a friendly Midwife with a cauldron.


Exilium (2)
◌ 1st Sifler is on an isle.
◌ 2nd Sifler's hideout is in a tunnel below the place where a Noble Lady walks her pet lizard.


Katib (3)
◌ 1st Sifler is in the village.
◌ 2nd Sifler is at the entrance to the Sacred Tower.


◌ 3rd Sifler is in the depths of the Sacred Tower. At the top of the Tower, go past the Altar and drop down a ledge, then walk along the outer side of the wall.

Enter the room with a ladder, turn left and go back outside, then drop to a ledge below. Right next to you will be a ladder that leads to the room where the Sifler is.


Edith (2)
◌ 1st Sifler can be reached from the 2nd belltower. Look for a hole in the walls on the top floor.
◌ 2nd Sifler is next to an Altar on the path to the 3rd belltower and the courtroom.


Blessedland (2)
◌ 1st Sifler - jump from the edge of the large arena where a dying Demiurge is. Once you reach the Sifler he will run away, and re-appear in the tunnels.


◌ 2nd Sifler is in the same room as the old priest.


Karst Cave (2)
◌ 1st Sifler - a passage to the Sifler is behind a bookshelf in the room with two Sanctifiers and a High Priest.


◌ 2nd Sifler is at the very end of the Karst Cave.

Naturalist
Satisfied all Heggies


Feed all Heggies. There are five in every location.
◌ Purple Heggies hate Bone Fragments.
◌ Blue Heggies hate Anthozoan Bones.
◌ Golden Heggies hate Health Potions.
If you accidentally pissed off a Heggie it will be back after you rest at an Altar.

★ Heggem
[1] can be found in the same puddle as the first Predator.
[2] is in the mine, to get to it jump from a ledge in the room with an Altar.

[3] is on the opposide side of the broken bridge, can be reached from the mine.
[4] can be found on the path which leads to the boss.

[5] use an elevator on the boss’ arena to get to the last Heggie.


★ Adamina
[1] is outside of the room where you meet Elmar.
[2] is sitting on a rock near the swamp.

[3] is below the Place of Newborns.
[4] is below the ladder on the way to the dungeon.

[5] is by a locked gate.


★ Exilium
[1] is on an isle.
[2] is at the base of the overgrown tower that leads to the gated shortcut.

[3] is on the outer walls of the Chapel.
[4] is on the rock next to an elevator.

[5] can be collected after defeating Exilium boss.


★ Katib
[1] is below a tree in front of a small stone bridge.
[2] is next to a waterfall in front of the cavern with horses.

[3] is on a rock above a boar and two lizards.
[4] is in the altar room.

[5] is outside of the tower.


★ Edith
[1] is underneath a small stone bridge that that leads to the first belltower.
[2] hides behind the third Altar.

[3] sits behind a house that has a Noble Lord hiding on its roof.

[4] is below the courtroom's walls. To get to it take the path between stairs from the courtroom and the 3rd belltower's bridge.

[5] is on the seashore which becomes available after you defeat Edith boss.


★ Blessedland
[1] below a long ladder that leads underground.
[2] jump down from the ledge of the arena where a dying Demiurge is.

[3] can be found underground on the way to the Chapel, at the end of a small path next to a locked door.

[4] hides behind a pillar in the Trinity Yard.

[5] is in the Trinity Hall. Right next to a hole in the wall that connects a meeting room to the grand stairway the stairs are collapsed. The Heggie is inside the tunnel.


★ Karst Cave
[1] is at the very bottom of a spiral staircase that's connected to the location's entrance.
[2] is not far from a fellow courier's cell.

[3] to find this Heggie drop down to a level below from a bridge that is surrounded by caged Lightheads, then walk outside. The Heggie hides between pillars.

[4] can be found in prison cells, right past the bridge where you use a lever to release the old man.

[5] the last Heggie can be found on the ground floor of the prison, behind a wall right in front of the ladder and stairs that lead to the nearest Altar.




Dark Mist Traveler
Explore the dark mist


See the next achievement, "Dark Mist Lord".


Dark Mist Lord
Explore all Dark Mist areas


These two achievements' titles and descriptions are misleading – locations that you need to visit are called Lost Valleys. There are five total.

Heggem: use an elevator on the boss’ arena, then walk across the rooftops to reach the entrance.


Adamina: On the left side of the stone bridge that leads to the Oracle Site is a set of wooden platforms which lead to a tunnel below the bridge, the entrance's inside.


Exilium: jump from the elevator to a rock next to it.


Katib: climb the ladder to the house above a boar that guards a chest and jump down to a giant rock next to it.


Edith: the entrance is hidden on the seashore, to the left of Jerold’s ship. You have to defeat Edith chapter boss first to unlock the seashore.


◌ Lost Valleys used to be called Dark Mist areas and were renamed after Deep into the Dark Mist DLC's release, but the achievements weren't.

Normally each ending requires its own playthrough, but you can get them all in one run. Fulfill requirements for all endings (they aren't mutually exclusive) and copy your savefile in the Load Game menu before defeating the final boss. Make your choice, reload, repeat.


Persistent



Default ending, does not require any additional actions to obtain.
◌ After defeating the final boss accept the drink.


Transcendent



In order to get this ending you need to find and upgrade Pitch-Black Melos Bottle 5 times.
◌ See chapter 3 of Trophy guide on how to get and upgrade Melos Bottle.
◌ After defeating the final boss refuse the drink.


The Answer



This ending requires to upgrade Pitch-Black Melos Bottle and to complete Tides of Oblivion DLC.
◌ Upgrade Melos Bottle to +5.
◌ Complete Tides of Oblivion DLC.
◌ Speak to Jerold in the Carriage.
◌ Speak to Jerold after defeating Karst Cave chapter boss, Usurper.
◌ After defeating the final boss choose “Put the Seal of Yekub in”.

Note that getting this ending in subsequequent playthrough(s) will require completing ToO DLC again. If you plan to unlock endings "as intended", with no save scamming, consider unlocking Answer on Journey 1. This way you won't have to fight buffed DLC bosses in later playthroughs.

New Journey
Start the second Journey


Defeat the final boss and move to NG+.


Imperishable
Acquire Imperishable Melos Bottle


NG+ achievement. Awarded for upgrading Pitch-Black Melos Bottle 9 times.
◌ For more detailed information on Melos Bottle check chapter 3 of Trophy guide.


Super Human
Activate all the Talents at the highest level


NG+ achievement. Awarded for maxing out all playable characters.
◌ Doing that requires a total of 23 Immundus Diamonds; 28 if you count Jerold (who has his own achievement). Check out this guide if you need help finding them.


Legendary Courier
Complete the 4th Journey or above without using the Egg of the Bearer


To get this achievement you have to beat the game 4 times on the same savefile, without using the Egg of the Bearer on the last run. Cannot be unlocked on the casual difficulty.

◌ The Egg of the Bearer is an easy mode (not the same as casual difficulty) which can be turned on and off by interacting with a statue in Heggem's mine. You can safely use it in the first three playthroughs.

◌ Prepare before moving to Journey 3: level up your team to 99, collect +5 Dark Mist Trophies, stock up on consumables and crafting materials, and unlock remaining achievements.
◌ There's nothing new to be unlocked on Journeys 3 & 4, all you have to do is defeat story bosses. You don't need to do sidequests, collect loot, or fight enemies between boss fights. Use Jerold to speedrun levels.
◌ Backup your savefile before each boss fight to avoid losing consumables on death and having to farm for crafting materials.
◌ Once you max out Melos Bottle there's no point fighting bosses in the Lunatic state anymore (unless you just feel like it), so keep a stash of sanity potions.
◌ Some boss tips: To beat Proxy Higgins equip vs Sendril trophies and use a Blessed Brute Force/Elixir of Epiphany (atk boost) & Blessed Elixir of Energy (infinite stamina for 30 sec), then spam light attack.
Final boss is also a Sendril and deals shadow damage, so get 2x +5 Brass Mask and vs Sendril trophies. You can interrupt nearly all of their attacks by doing a heavy attack 2 times fast enough

Challenge
Complete the game with Altar Level 1


Awarded for completing the game without leveling up at all. Using Starry Honey Wine to respec does not work, as it does not reset your Altar Level. Has to be a full lvl1 playthrough. Completing ToO and DitDM is not required.
◌ Eggy: allowed.
◌ Casual difficulty: not allowed.

Lvl1 run in Pascal's Wager is pretty forgiving. With the right trophies you deal decent enough damage to comfortably clear out locations and defeat bosses, and do not get one-tapped at any point even without the Egg of the Bearer.

I finished my lvl1 playthrough with the following:
◌ Attack: Father's Love, Fanatical Sand (replaces Discipline), Melos Bottle. Try to kill as many bosses as you can in the Lunatic state to avoid permanently handicapping yourself in the endgame. Both FL and FS can be reforged with vs. Sendril for the final boss.
◌ Physical defence: Pale Egg, Basilisk’s Nirvana
◌ Shadow defence (for the final boss): Basilisk’s Nirvana, Figurine of Sorrowful Nun
◌ Remaining nightmare slot was reserved for Non-Existent Boots (exploration), and Glory (combat) which was replaced by Concentration Rune in Karst Cave.

Pascal's Wager
Get all 'Pascal's Wager' Trophies


A very misleading description for multiple reasons. Pascal's Wager has an entire category of collectibles called "Trophies" which have nothing to do with this - this achievement requires to obtain all achievements tied to the main campaign...but apparently only those that were in the game back when it first released on iOS/Android.

The list of required achievements, in the same order they're listed in the guide:

• Story achievements:
  
  • Crazy Prologue
    
  • Father & Daughter
    
  • Wedding Under the Moon
    
  • The Banality of Evil
    
  • Deicide
    
  • Demiurge's Destruction
    
  • The Apostasy
    
  • The Cultists
    
  • My Love
• Missable achievements:
  
  • Nightmare
    
  • The Truth
    
  • Heavy Armed
    
  • Witness
    
  • Whisper of the Heart
    
  • Death Knell
    
  • Escape from Madness
• Misc. achievements:
  
  • Ascetic
    
  • Alchemy Apprentice
    
  • Druggist
    
  • Victory
    
  • Merchant in the War
    
  • Blacksmith
    
  • Ingenuity
    
  • Beginner
    
  • Grandmaster
    
  • Loss of Sanity
    
  • Crazy
    
  • Illusion
    
  • Chivalry
    
  • War and Destiny
    
  • Blood Ties
    
  • Hand in Coffin
    
  • Redemption
    
  • Alchemist
    
  • Wisdom
    
  • Hide and Seek
    
  • Naturalist
    
  • Dark Mist Traveler
    
  • Dark Mist Lord
• Endings:
  
  • Persistent
    
  • Transcendent
• Subsequent Playthroughs:
  
  • Challenge

Although Obsession Challenge is a standalone mode, playing it requires to load a savefile from the main campaign. Chosen savefile determines which bosses are available to battle and more, so to be able to get any achievements in this mode you first need to beat the main campaign.

◌ Using multiple characters to defeat different bosses is allowed.
◌ You can freely use consumables in the Obsession Challenge - you get them all back between bossfights.

For Teresa



To get this achievement you must defeat the final boss with any character other than Terrence. Can be done on Tyro difficulty.


The Obsessed One
In the Standard Mode of Obsession Challenge, defeat all the Obsessed Ones in the main story.

Awarded for defeating the following bosses in the Standard Mode: Maddened Ascetic, Holy Father, Jenny of Exilium, Rosen Cavailer Patrick, Fused Sprenger, Frollo, Edith, Elena, Proxy Higgins, Usurper, The First Messenger
◌ In the Standard Mode each character has their own fixed Trophy and inventory loadout which cannot be changed. Talents unlocked in the campaign carry over.


Eternal Colossus
In the Custom Mode under Colossus Difficulty of Obsession Challenge, defeat all the Obsessed Ones in the main story.

Awarded for defeating same bosses on the Colossus Difficulty.
◌ Unlike the Standard Mode, in the Custom Mode you get to play as your characters exactly as they appear in the main campaign - their current level and unlocked Talents, all collected Trophies, full inventory. A lvl99 team with lvl5 DitDM Trophies and pockets full of blessed potions is recommended.

One of worst hardest bosses in this mode (imo) is Proxy Higgins, because of his bloated healthbar. To beat him use Terrence or Benita with the best vs Sendril trophies equipped. When the Proxy is about to start casting his timed nuke drink a Blessed Brute Force/Elixir of Epiphany (atk boost) & Blessed Elixir of Energy (infinite stamina for 30 sec), then spam light attack. The window is extremely small, but it's doable.

Untouchable
In any mode of Obsession Challenge, defeat all the Obsessed Ones in the main story without getting injured.

Awarded for defeating same bosses without getting hit.
◌ Can be achieved on Tyro difficulty. Using Elixir of Epiphany is allowed.

◌ I mostly used Jerold to get this achievement - he outruns nearly all bosses without even needing to dodge, which instantly removes a good chunk of risk and difficulty.

You also can cheese some bosses with Viola's counter Talent - with some preparation she one-taps them on Tyro. Credit for this strategy goes to knight_kei on reddit, here's their video showcasing it.
◌ Respec to max out Viola's damage and crit rate, put on Trophies that increase crit rate/crit damage & damage vs enemy type. Check this guide for each boss' type.
◌ At the start of a fight switch to Shock bullets (and drink an Elixir of Epiphany if you have enough time), then parry. Without the potion you will have to parry multiple times, or finish the boss off normally.

Dance of the Throne is a standalone DLC campaign slash speedrun mode. With an exception of two achievements that require to play the campaign on hard difficulty all achievements can be obtained on the first playthrough.

◌ If you're like me and seeing the timer gives you anxiety, it can be turned off in the settings. There's only one achievement that is time-dependant, and it's not even available until you beat the DLC once.


First Awakening
Clear Dance of the Throne for the first time.

Awarded for completing the DLC campaign.


Demiurge Dancer
Activate all of Elena's talents in Dance of the Throne.


You need to max out Elena’s Alchemy/Attack/Special skill trees, which can be done as soon as you arrive to Edith if you take your time to look for upgrade materials in each level.
◌ Unlocking Blade Dance skills is not required for this achievement.


Lost in a Dream
Obtain the mysterious item in Blessedland.


◌ Defeat this group of Takolas to obtain a key to confessional booths.

◌ Unlock the booths and defeat all enemies. A consumable will appear in the middle of the room. Free some space in your inventory and pick it up to unlock the achievement.



Return to Sender
Deflect 10 ranged attacks in 10 seconds.


Easiest to do in the Blessedland by provoking this group of Takolas. One parry can deflect multiple projectiles. This achievement can be obtained in chapter replay.



Deadly Elegance
Use Sword Dance - Lone Shadow to dodge 3 incoming attacks while attacking.


Awarded for using Lone Shadow to dodge 3 attacks in a row. Maddened Ascetic is a good target; his attacks are slow and have a long wind up time. This achievement can be obtained in chapter replay.

Following achievements are granted for finding and defeating secret mini-bosses in each level. Doing this also unlocks Elena's Blade Dance talents of same names.
◌ This part of the guide contains spoilers for the main campaign.


Legacy
Find and defeat all the Obsessed Ones from the Nightmare in Dance of the Throne.


Missable. Awarded for defeating all Obsessed Ones on the same campaign savefile. Individual achievements can be obtained in chapter replays, but not this one.
◌ If you missed any on the first playthrough you can get this achievement on Journey 2 by defeating the remaining Obsessed Ones.


Shadow Moon
Defeat the Obsessed One of Heggem


◌ Pick up a Butterfly Stone from the Bearer statue in the Mines.

◌ The Obsessed One will appear at the campfire, the one where you start the main campaign.


Path of Suffering
Defeat the Obsessed One of Adamina


◌ Get a Hand-made Puppet from a cage at the starting location.

◌ Give the puppet to a dying mother at the Place of Newborns.

◌ Climb the nearby ladder to find the Obsessed One.


Fleeting
Defeat the Obsessed One of Exilium


◌ Collect Argil x3 across the map.
1st Argil can be found in a chest near a locked gate guarded by a Church Spearman. 2nd is next to the wall where Patrick can be found in the main campaign.

◌ You get the 3rd Argil for killing a trio of Church Warriors.

◌ After collecting all three interact with a giant tombstone behind the chapel to spawn a Butterfly Stone.

◌ You will find the Obsessed One in the chapel.


Eternal War
Defeat the Obsessed One of Katib


◌ Gather four Anthozoan Bones – they can be found at places where you meet Drake in the main campaign:
1 - at the upper entrance to the Sacred Tower; 2 - near the bridge where you meet Drake for the first time

3 - In the village, not far from a boar and 2 lizards; 4 - near the main entrance to the Sacred Tower

◌ Deliver the bones to the Gravedigger to get a Butterfly Stone

◌ Head to the top of the Sacred Tower, you will find the Obsessed One in the altar room.


Demiurge's Wish
Defeat the Obsessed One of Edith


◌ Pick up a Greasy Candle on the beach. Interact with one of doors in Edith to get a Tower Key.

◌ The key unlocks an entrance to the 3rd belltower from the lizard-infested cave with an Altar. Ride the elevator up and pick up a Butterfly Stone on the bridge.

◌ Head to the courtroom. It will appear empty from the outside, but once you enter a bossfight with the Obsessed One will start.


Finale
Defeat the Obsessed One of Blessedland


◌ Collect 4 sword fragments from the four Holy Pillars across the Blessedland, then kill Eleanor the Demiurge to get Bloodstained Tristram. Eleanor spawns after you get all sword fragments.

◌ Interact with the statue in the Trinity Yard to get a Butterfly Stone.

◌ Head to the place where you fought Elena for the first time in the main campaign.

Note: this fight was bugged for me - when i was using Elena's default outfit i either couldn’t deal damage to the Obsessed One, or they didn’t spawn at all. If that happens to you too you might have to switch outfits and then reload multiple times to get the fight working.


Path of Truth
Defeat the Obsessed One of Karst Cave


◌ Pick up Eckhart’s Cane Sword in Viola’s cell

◌ Come back to Norwood and commit suicide by jumping from the balcony he’s sitting on. When you respawn a Butterfly Stone will appear behind you.

◌ The last Obsessed One will be waiting for you on the path that leads to the Usurper.

These achievements require to beat the DLC campaign on hard difficulty, which becomes available after you beat it on casual or normal. Both achievements can be obtained on Journey 2: after completing the campaign load your savefile and change the difficulty. On Journey 2 you keep all unlocked talents, including passive Blade Dance skills.
◌ Both achievements cannot be unlocked in chapter replay.


Endless Nightmare
Use Elena to clear Dance of the Throne on Hard Difficulty.


Awarded for completing the DLC campaign on hard difficulty.


Empress of the Eternal Night
Obtain an overall S rank for Dance of the Throne in Hard Difficulty.


Awarded for getting S rank in every single level of the DLC on hard difficulty.

Rank is affected by your time and score.
◌ Picking up blue upgrade materials decreases time by 30/60/90/120 seconds. That stays true even after you upgraded all of Elena's talents and interacting with blue collectibles stops giving you items.
◌ Defeating enemies, Obsessed Ones from the Nightmare, and bosses increases the score.
◌ Other actions - saving, dying, using consumables, etc - affect neither the timer, nor the score.

I do not know S rank thresholds, but with an exception of the final level (which has a time limit of 7 minutes) they seem to be pretty generous. Here's my time for each level for the reference. All kills/collectibles.
◌ Heggem: 19:57
◌ Adamina: 23:21
◌ Exilium: 33:55
◌ Katib: 28:06
◌ Edith: 14:35 (the level is full of collectibles that reduce time)
◌ Blessedland: 37:48
◌ Karst Cave: 14:49 (also a lot of collectibles that reduce time)
◌ Colossus Grave: 6:43 (time limit is 7:00)

Boss advice:
◌ Blessedland: use double blades + Elixir of Epiphany (attack boost) + Elixir of Energy (endless stamina for 30 seconds) to defeat the boss.
◌ Colossus Grave: save up as many consumables as you can for the final boss, especially Elixirs of Epiphany, Hound Amulets, Elixirs of Energy, and Elixirs of Recovery. Time limit's pretty tight, and you do not have the luxury of circling the boss while waiting for a safe opening. In the 2nd and 3rd phases do 3-4 heavy attacks with double blades, back off for a moment to avoid triggering a parry, repeat. The only spell which cannot be interrupted by repeated heavy attacks is when the boss surrounds themselves with a vortex of birds. And make sure to skip cutscenes, they do not pause the timer.

Also unlike the main campaign, here you cannot backup your savefile via ingame menu, and there's no option to replay a chapter upon completion if you got a lower rank either. So practice beating chapters in the chapter replay mode, and maybe backup your save folder before making a real attempt.

Pascal's Wager savefiles are located in C:\Users\name\AppData\LocalLow\TIPSWORKS

This is especially useful for the final boss, since the game autosaves before showing you the score.