These achievements are easy to miss in most cases, as you kind of have to go out of your way to get them by progressing in a very specific, non-obvious way.

This one can be earned right at the start of the game, in Borrington, but it's not very intuitive. You have to earn 10 Frequent-Flyer Miles and talk to the gate guard. Once the conversation is over, go to you inventory, and just use the Miles as if you were opening a door with a key. Only this will start a special dialogue and let you leave the town. I don't know if any other guard is able to be bribed in the game. Be aware that this will break your quest line - you will be able to traverse the world, but you won't be able to advance before you do the tutorial, talk to the recruiter, etc., even though some characters will point out that you're not supposed to be talking to them yet.

You will arrive at a point in your quest that demands a Crossbow in order to leave Bowtudgel, otherwise Tabitha will not let you. You need to get a credit card to be able to amass enough money for the Crossbow. To get around this, get some Miles and go to the Docks in Bowtudgel and pay to be transported back to Borringshire. Behind one of the nearby barns you can find two chests containing the Crossbow and 50 Crossbow Darts.

To reach Ufiyya, you'll need to keep up your Hydration Level throughout the short journey. Before you get a single Electrolytesportsdrink in your inventory, you must reach the city with other means. A lot of different beverages replenish your Hydration Level, but just by a miniscule amount. The best thing to do is to get a couple hundred glasses of Water for free from Borringshire or Bowtudgel and then, when your Hydration Level is low, rapidly hit TAB and click a Water, then immediately hit TAB again and repeat until your meter replenished. You have to be fast, because it depletes rapidly.

This really should have numbers switched with 104. Because, provided I am not mentally challenged, you get the first Subplotkey from the Château, and then get the second one from the desert. If you go to the Catacombs unprompted, then even if you circumvent the rock, you can't enter, because you won't be able to interact with the Keycard slot. Unless these achievements were ranked not chronologically, but rather by their arbitrarily defined difficulty, or the level of skill or knowledge advancement, following the class naming context. But this doesn't make much sense either when we examine the percentages of people who achieved each one.
But I digress. When you are finally tasked with reaching the Catacombs, when you arrive at the rock, just look to your left, you'll notice that the mountain's incline is getting lower and lower. Simply climb the rocks from that side. Jump into the pass from the other side of the rock and you can enter the Catacombs.

This is rather easy to do due even randomly or unwittingly due to one simple fact - you don't even need to help the Lion to progress. It only gives you, like, 10 Crossbow Darts and the correct item to give to him is purposefully made unintuitive, since he keeps asking for pure meat without plant matter, and the only correct answer is a vegan analogue which can be obliviously eaten by Lance after fighting some cheaply spawned zombie cheerleaders.
Wait, what? Anyhow, just ignore the Lion, you can always go back and help him after you get the achievement. But keep in mind that the required item can be found only twice throughout the entire game.
Here is the breakdown of what each animal needs and the reward it provides:

Animal

Give

Receive

Ass

Zackpro

Jackhammer Key

Bear

Earmuffs

Train Key

Doe

Painting of Springtime

Earmuffs

Lion

HerboMeat™

10 Crossbow Darts

Duck

Take it to the Bathroom and put it in water

Fork Key, 5 Crossbow Darts

These are technically missable, but very easy to load an earlier save and do them quickly due to simple requirements. They all require you to hold a pot in your hands while encountering a non-repeatable cutscene at some point in the game (with the exception of the last one).

Have a pot in your hands when you meet Margaret for the first time. Go to Borrington and pick up a pot. Leave and then find Margaret at Sandal Falls to the south. The only remotely tricky part about this is having to navigate without a map, since you have your hands full, but you can just follow the river. Be sure to check the treasure behind the waterfall while you're at it.

Have a pot in your hands when you leave the Palace in Bowtudgel for the first time, after being briefed on your "Quest" in the War Room. In theory you can have a second attempt when you're returning to the War Room with your first Plotkey. Gary will be waiting at the Palace gates - you have to go to Borringshire or Brobensy for a pot and carry it all the way from there - if you jump within the palace walls while omitting Gary, it will make the game skip the cutscene entirely. For me it didn't work, though, IIRC. If you try it like that, let me know if it worked.

Have a pot in your hands when you first leave Bowtudgel, regardless of which exit way you took. If you've sequence broken out of Bowtudgel first, then go back, take a pot from the Palace and then leave.

OK, this one isn't missable after all. You can always go to the Emir while holding a pot and this will unlock the achievement.

You don't really need to take down all of her health bar with the Crossbow, thankfully. Dealing damage to it this way is frustrating enough as it is. Be prepared to have ~150 Crossbow Darts on you to avoid retrying to often. Whittle her down with a melee weapon until the left edge of her health bar reaches the underside of the letter "m" in her name, like this:

Then finish her off with a Crossbow, a single successful attack should be enough.
See Dragonslayer if you want to know how to defeat her at all in the first place.

Technically missable if you just take the test and fail and move on with the game, that's why it's in this category. It's not clear to me what you have to read first or whether the game even checks if you did. It does check (one would hope) whether you tried for the first time on your current save file.
I would recommend at least reading all the exhibitions at the Scenic Overlook and all the material from the "libraries" - Borringshire Gym book corner, Ufiyya Library and your own book nook in your room in Limbo. Personally I'd just wait until after the main "quest" just to be sure.
Then see History Buff.

This seems to be missable! If you don't do it before recovering the Subplotkey, the R.O.N.S. will go to a protest! At least it's not possible after you've finished the main "story". Buy the letter opener from the Stationery store in Bronsby. Give it to Tabitha via the full inventory app. It will unlock her killing move when exploring the R.O.N.S. Lair - it only works when you are aiming at a nearby rat.
You don't have to kill Ralph.

This is a pretty fun quest, so I'd advise to try it yourself.

Here are the steps required to complete the investigation:

1. Go to Tivany Hall ScrÏptôrium at The University of Brobensy.
   
2. Talk to everyone there (explore all the dialogue options).
   
3. You will learn the possible password to Addison's desk, but you'll need a Goosequill
   
4. Exit the Hall, you will trigger a cutscene
   
5. Buy the Goosequill at the Stationary in Yuresipitor Hall.
   
6. Go to Addison's desk and write "trouble". You'll get Addison's Diary.
   
7. Talk to everyone again.
   
8. Try to exit the Hall, you will trigger another cutscene.
   
9. Go upstairs to the Libráry Staques and come near the victim to trigger a cutscene.
   
10. Talk to everyone again and go back to the latest victim and talk to Remmy. You'll learn you can buy a map of the Libráry Staques.
    
11. Go to Department of Cartography at Troangar Hall University of Brobensy and buy two Maps of The Library. Give one to Tabitha (optional, but makes things a lot easier).
    
12. Go back to the Libráry Staques, you'll trigger a cutscene with Sevra on the way.
    
13. Find the Study Hole by first flying to it with Tabitha equipped with a Map and locking it in place, and then following her there. Enter the Hole, you will trigger a cutscene. You will get the Penrose West 200-B Stabilized-Release Crossbow.
    
14. After the cutscene, pick up the Murderer's Map of the Library from the floor near the body.
    
15. Find the Scorpion Pit and walk over to Malek to trigger a cutscene. You'll get the Key Fob for the Library's Main Office.
    
16. Find the Main Office and use the Fob from the quick access menu to open it. Talk to George. You will enter a dialogue in which you have to make your final accusations.

To unlock the achievements, you need to make correct choices.
Here are all the correct answers (requires all the evidence):

• Who murdered Addison? George
  
• Evidence to support your accusation: Addison's Journal
  
• Who murdered Winifred? Barrie
  
• Evidence to support your accusation: Penrose West 200-B Stabilized-Release Crossbow
  
• Who murdered Barrie? Malek
  
• Evidence to support your accusation: Murderer's Map of the Library

If you do this correctly, you will receive lots of awesome loot:

• 2 Rugby Tickets
  
• Pot Popper
  
• Deerstalker Cap

Just what it says, use a melee weapon like a Sword or a Scythe.

These achievements you will be able to attempt at any point in the game, even after completing the main "storyline" (assuming you already reached the necessary places).

Successfully use an alchemy recipe at any of the alchemy vendors.

For each piece of furniture Andria will give you 200 Frequent-Flyer Miles. Just make a note (I recommend the notes app in the Steam Overlay) of which pieces you have already found or given to her, so it will be easier to track down the remaining ones when the time comes.

• Rowena Mirror - Château Living Room
  
• Rowena Arm Chair - The Fishbowl at Yuresipitor Hall in Brobensy
  
• Rowena Sofa - Château Reading Room / Study
  
• Rowena Nightstand - Kertrude's House (Sidepiece Side Quest)
  
• Rowena Chest - Eastern dead end in the Southern Catacombs
  
• Rowena Bed - Desert Inn Mezzanine Suite 201 in Ufiyya
  
• Rowena Table - Inside the lower waterfall at Tawsiary Falls
  
• Rowena Console - Haguthy Hall, Room 307 at Brobensy

Obtain the App from one of the chests. Then select XY-Plot Mode in Radians and input:
x✖️x➖3️⃣✖️x➕2️⃣
Then hit Plot.

You will get a message about unlocking the new location. You can simply go there by boat. Sadly, there's almost nothing there.

You will do this at some point, if you're playing correctly.

Just use the Background Music Changer App.

Really easy to do by mistake. Even if you don't have any boots, you should be able to easily jump off the Scenic Overlook.

After obtaining the App in Bowtudgel, just play it and don't get any mistakes. You can do it on the easiest level.

Just talk to her, dude... Tell her what is it that you want... It's one of the most useful features in the "game".

Go to the Regal Armory and Outfitters at Bowtudgel. Try the Tuxedo on in the Changing Room with a couple of Espressos in your inventory. Drink one - each will deal you 3 Spleens worth of damage due to heart palpitations. Drink another one when they stop, until you die while wearing the tux and unlock the achievement. The Stovepipe Hat has the highest armor rating of all the hats in the game.

The easiest way to do this is first making sure your Coin Bag can hold that much. Then remove the rock from the pass leading to the Catacombs with Gauntlets of Might. As a reward, your Coin Bag will be topped up to whatever amount it can hold.
ProGamer™ Tip: You can earn a free Coin Bag Upgrade by killing all the R.O.N.S. at Lady Samiltish' cottage.

Done at Bowtudgel Shooting Gallery. I'll let you figure that one yourself. It requires skill.

This takes time. As soon as you have the credit card, use it to buy upgrades for your money bag so you can carry 1000 Frequent-Flyer Miles. There is no item more expensive than that, so you won't need further upgrades for some time. Then buy anything you want to bottom out your credit at 1000. Make sure in the banking app that you disable any autopay and such. With each renumeration period your credit score will lower, starting at 600 and ending at 300, unlocking the achievement (not sure if it's possible to go lower than that, but it's not necessary). You can then work towards paying your dues, so that you can use the card again. Note that it also takes a while for the bank to re-enable your credit card if it has been declined, after you pay up.

There is a very specific wall that you need to find. It's easy to miss. It's that "horizontal" (meaning going from West to East) that is North-East of the Scenic Overlook, between the river and the construction site fence.

Just buy one and use it. It's one of the intended ways to make money (see Making Money section below).

As soon as you're in the overworld, you can go to the Ranch and abscond with one of the animals.

First you need to have a Lute. Buy a Lutebox in the Lutebox shop at Ufiyya. Open it - it contains a Lute (duh). Also buy some Sheet Music for Greensleeves from the Desert Bazaar. Then stand near the oasis in the middle of the city, more or less at the spot that Ronald Ouingay strides through. First, you need to learn how to play, keep playing until you can play Greensleves. Finally, play Greensleeves and finish the song without skipping. A cutscene will trigger.

Melee Fyrena Hyrde.

Go to the University of Chingaim Haguthy Hall at Brobensy, Room 303. Interact with a desk - you'll take part in a calculus lesson. Equipped with this newfound knowledge, talk to Achilles and you will convince him about the importance of infinitesimal values. He will reward you with Koofers.

You will unlock these achievements as the game progresses (if you can call it "progress"), regardless of your specific actions:

You have to do this to attract the attention of a recruiter.
Good luck. You're gonna need it.

It's the whole point.

There is no option to not accept it, so there.

"Defeat" might be an bit of an overstatement, but it's not exactly straightforward anyway.
The hint for this is in Death's library.
Instruct the Strong Female Protagonist to attack the turtle shells while you must strike the tail.
Your first hit is free. After that, move away from the "Dragon" until it starts to spin. After a moment it will coil itself and rush you with its tail winded, usually to your right side - be prepare to adjust your position and hit the tail as it's coming your way. It takes just a couple of hits to defeat her.

In this game, there are 3 ways to make money.

This strategy is described in detail in a book in Ufiyya Library, so I won't get into the details. It's not recommended anyway.

This is the basic workflow:

1. Obtain the Pot Popper by completing the Library Murders quest (optional, but you'll lose your mind without it)
   
2. Buy a bunch of Wands of Polymorph
   
3. Go to an optimal farming spot
   
4. Break all the pots
   
5. Exit
   
6. Come back
   
7. GO TO 4 unless you are already sick of it
   
8. Go to a pawn shop that will buy Artifacts off you
   
9. Sell only Keycards, Monoliths and Letters of Transit (in other words, anything that is worth more than a couple of Frequent-Flyer Miles
   
10. Use a Wand of Polymorph
    
11. GO TO 9 unless you've ran out of Artifacts or Wands of Polymorph
    
12. Repeat the whole shtick if needed
    
13. ????
    
14. PROFIT!!!!

Even with the Pot Popper this is extremely tedious.
Here are the only 3 valid farming spots, depending on where you are in the game:

• Bowtudgel - Regal Armory and Outfitters entrance - 4 pots
  
• Brobensy - Haguthy Hall, Room 305 - 9 pots
  
• Ufiyya - Pillared structure near the oasis - 16 pots

You might have noticed, that a couple of places give out Water for free, while you can sell it for 1. By employing an autoclicker set to a low ms interval, you can leave the game running, selecting thousands of Waters to be bought. Then you can pawn them all for 1, also using the autoclicker. The best way to do this is the Bowtudgel Market, since the places to buy and sell are, like, 3 meters away from each other.

Acquire the Developer Key from the Southern edge of the overworld map. It will enable you to hit F5 to set your current money to 1000. Apart from the Money Bag Upgrades, there are no purchases in this game worth more than 1000.

(let me know if you have any possible Fortune Cookie tips or explanations to add here)

• Although Death has no secrets, Death's library might.
  
• Anagrams are wit for the witless.
  
• Help! I'm trapped in a Chinese food factory!
  
• If you're one of those people who always blows through every conversation and cut scene, this game isn't for you.
  
• Lucky Numbers: 79, 86, 85, 76, 84, 73, 78, 69?
  
• Most long passages in this game's various libraries are just supplementary information and you don't actually have to read them.
  
• The view from the rooftops of Bowtudgel City can be quite stunning. (See the Loot section of this guide for a description of this secret)
  
• There is a dragon haunting the Southern Catacomb. ... No, not the dragon you're thinking of. ?
  
• They say a good time to die is when you're borrowing something. (See Glitching achievement)
  
• They say a Scholar's Cap is very useful protection against brain damage.?
  
• They say Carmeana is so well suited to the role of future monarch that the King's gonads didn't bother trying after that.
  
• They say one of the enemies in this game was inspired by a dream. (I don't want to know which one)
  
• They say that if there's something in this game you can't figure out what it does, it's probably because this is only a third of the full game.
  
• They say that if you find yourself with too much of a good thing, keep searching and you might find yourself with just enough of a good thing.?
  
• They say that if you want to achieve maximum purse size, it's a good idea to build up your credit early.
  
• They say that the great warrior Achilles is very talented at abstract mathematics; but not so much at applied math... (See Zeno's Paradox achievement)
  
• They say that there is more than one way to cross the desert. (See Sequence Breaking 102 achievement)
  
• They say the Archduchess of Khennora is hiding out somewhere in this kingdom.?
  
• They say the daughter of the mayor of Banskera is not like other Banskerians. ?
  
• They say there is an item in the game that is not a weapon, but that can be used as one in the right situation. (probably referring to the Letter Opener - see Ratslayer achievement)
  
• You are about to go on an adventure.

• If you have the Galilean Sandals, you can save yourself from falling into water by equipping them mid-air.
  
• Getting the Ratslayer achievement is a unique opportunity to get a free Money Bag Upgrade and also a Spleen if I'm not mistaken.

Submit your own!

• What does the Enemy Pacifier even do?
  
• Is the Statuette really useless?
  
• Can the Refrigerator and Spare Ricohedron even be used for anything?
  
• Is there a way to use the Rugby Tickets? There is a rugby field north of Brobensy, but it's inactive. Like most of the game.
  
• Is the Gift Certificate broken?
  
• How do I make Tabitha wear the Steel Bikini?

The way alchemy works in this game is unbelievably dumb.
Talking to an alchemy vendor lets you buy alchemical ingredients, but they never go into your inventory. Rather, they are used up on the spot. You can't find them on your own elsewhere.

To create an alchemical concoction, you have to purchase the right amount of each reagent.

Alternately, you can buy multiples of the required amounts of ingredients to receive a multiple of the desired item.

For example, if you buy 9 Roots of Hemlock and 6 Galls of Goat, you'll get 3 JJ's Fruit-Aids.

ProGamer™ Tip: You can "craft" any alchemical recipe for free at The Château Escape Room.

Here is a list of ALL the recipies in the game (that I know of), along with their total cost in brackets:

Joke's on me - turns out that at least some of the loot is randomized, so all the notes I took about what I found where might be useless after all, apart from listing the chest locations.
Feel free to point out any chests that contain different loot in your playthroughs.

• 2 chests behind one of the barns in Borringshire - Small Crossbow, 50 Crossbow Darts
  
• Chest at Sandal Falls, behind the waterfall - Galilean Sandals (They let you walk on water. I wonder why it's Galileo and not Jesus though lol)
  
• Chest at the middle of the pond near Provencial Estates Vinyard - Randomized. I once got an Enemy Pacifier and another time I got the Anagramr App.
  
• Rowena Table inside the lower waterfall at Tawsiary Falls
  
• Chest at the south edge of the map - Skeleton Key. To reach it, go to the Imperial Beach, put on your Galilean Sandals and start moving in the direction as indicated below. If you reach the edge and you don't see the chest anywhere on the horizon, scout out with Tabitha.

• Spleen behind the Gymnasium
  
• Chest in the gazebo in the town center - Background Music Identifier App
  
• Chest near the external wall behind the Formicarium - 5 Frequent-Flyer Miles
  
• Chest in the far corner of the General Store - 10 Fortune Cookies

3 items here are hidden behind a single secret location with branching paths. To go there, find the below spot, you should see a ladder:



Climb the ladder. Remember your training.



You will get on the roof. Turn left and see another ladder.



Approach and climb it.



After climbing it, turn left once again to see a wooden plank.



Walk the plank, yarr.



Now you are on the Palace rooftops - you can either go left or right.
If you go right, you'll walk around the Palace courtyard counter-clockwise and reach a higher structure with a ladder.



Climb it and a magical black cloud will appear to take you to the Spleen.



Going left, around the Palace courtyard clockwise, you will reach another fork in the road - either continue or walk off on another plank.



Continue on the roof clockwise to find a chest.



The plank leads to the roof of the Bank.



Now from the Bank roof you'll have to carefully jump on some roofs and into the Airport backyard that is closed off for another chest.



Good luck!

• Chest on the Palace rooftops - 100 Frequent-Flyer Miles
  
• Chest in the Airport backyard - Not-So-Speedy Boots (highest armor rating boots in the game)
  
• Spleen on the North-West building roof - get there from the Palace rooftop

• Chest behind the throne room in the Royal Palace (requires Skeleton Key) - Developer Key
  
• Chest in the River Market - Scovilr App
  
• Rowena Nightstand at Kertrude's House (Sidepiece Side Quest)
  
• Chest in the Scovilr Factory - Speed Boots

• Stovepipe Hat at the Regal Armory and Outfitters (see Glitching achievement)
  
  
  Brobensy
  • Chest near external wall - 100 Frequent-Flyer Miles
    
  • Rowena Arm Chair at The Fishbowl in Yuresipitor Hall
    
  • Rowena Console at Haguthy Hall, Room 307
• Chest at the Tivany Hall Libráry Staques which appears randomly (you need to progress the Library Murders quest to find it) - Randomized (I got the Anagramr App for example)
  
  
  Château
  • Rowena Mirror in Living Room
    
  • 2 chests in Living Room - 5 Frequent Flyer-Miles, 10 Crossbow Darts
    
  • Chest in North Bedroom - Painting of Springtime
    
  • 3 chests in the Upper Hall - Bee Key, Chicken Cosmo, 20 Crossbow Darts
    
  • Safe in Escape Room - Thumbdrive Key
    
  • 3 chests in Kitchen - 20 Crossbow Darts, 2 Fortune Cookies, HerboMeat™
    
  • 3 chests in South Bedroom - 15 Crossbow Darts, 10 Crossbow Darts, Nail Key
    
  • Chest in the Secret Room (Behind the bedroom walls, accessible through Bathroom) - Background Music Changer App
    
  • 3 chests in the Master Bedroom - Zackpro™, 20 Crossbow Darts, 50 Frequent-Flyer Miles
    
  • 2 chests in the Reading Room / Study - Frankfurter Key, 20 Crossbow Darts
    
  • Rowena Sofa in the Reading Room / Study
    
  • 2 chests in Cabal Room - Priest Key, Gauntlets of Power
    
  • 8 chests in the Mud Room - 4x 5 Crossbow Darts, 4x 5 Chicken Cosmos
  
  
  Ufiyya Desert Inn Mezzanine
  (require paying for Suite 201 or Skeleton Key)
  
  • Rowena Bed in Suite 201
    
  • Spleen on the Hotel roof
    
  • 2 chests on the Hotel roof - Graphing Calculator App & 100 Frequent-Flyer Miles
  
  
  Southern Catacombs
  • Rowena Chest in the Eastern dead end tunnel
    
  • Chest on the west edge of the lake - Gyro
    
  • Chest in the western one of the two small corridors leading out of the lake from the north side - 7 Fortune Cookies
    
  • 3 Chests in the No Longer Sacred Former Temple of Rico, hidden in a small room near the large middle room with 8 columns (use the switch on the east side to open it) - Spare Ricohedron, 100 Frequent-Flyer Miles, Statuette
  
  
  Hyrde Lair
  • 8 chests: 1000 Frequent-Flyer Miles, 5 Fortune Cookies, Gyro, Frozen Yogurt, HerboMeat, Beer, Chicken Cosmo, Goblet of Mead