The Good We Oft Might Win (Simple Poison Rules)

 Look freaks, you don't need pages and pages of dozens of different kinds of poison for your RPGs. Most purposes you need can be fully covered by a poison that kills quickly and violently, a lethal poison that is tasteless and odorless, a poison that is chloroform, a poison that causes gradual deterioration over weeks, and a nonlethal poison that makes you weak. That's it! You should still give it some panache, come up with a cool name for the poison and so on. But the mechanics should be simple.

Determine the "cost factor" for your setting. Poison costs will scale with that factor. The "availability" shows the chance you can find a meaningful supply in the right circumstances.

• Quick weakening poison. Obvious smell and color. Cost factor x1 Availability: 4-in-6.
• Quick knockout poison. Obvious smell and color. Cost factor: x2 Availability: 2-in-6.
• Quick lethal poison. Obvious smell and color. Cost factor: x3 Availability: 3-in-6.
• Slow lethal poison. No smell, dissolves totally. Cost factor x10 Availability: 5-in-6.
• Quick lethal poison. No smell, dissolves totally. Cost factor x100 Availability: 1-in-6.

The DM should determine the name, color, application (bloodstream, inhaled, consumed), what the right circumstances for finding a meaningful supply is, and any partial effect on a passed save, based mainly on vibe.

You can use this generator for symptoms: https://perchance.org/rpgsymptoms
Or this one. It's pretty good: https://blog.d4caltrops.com/2022/05/d100-deadly-diseases-alarming-ailments.html

Thief Hirelings

 Recently I was reading through my 1811 Dictionary of the Vulgar Tongue by Francis Grose, and in between all the amusing stories, cack-handed censorship, and racism against the Dutch I was inspired to make this table.

Thief Hirelings
In addition to the hirelings and retainers that can be found by scrounging taverns and putting up posters, a thief PC can find recruits who are a little less desperate and a little more skilled, the members of criminal society. You can give the thief PC a menu of villains and rogues when they touch base with the movers and shakers of a town's underworld. These hirelings are strictly better than the random and the desperate. They will always sign on for more jobs if the last one was lucrative, or if they're promised one last big score. They either have a specialty that succeeds with 4-in-6 chance or, if a robber, they have a thief's sneak attack ability. Finally, they have a thief's code of honor-- even if they make an enemy of the PCs, they'll never squeal when captured and will cover for PCs with the law.

Services:

Accomplices are half the price of a normal hireling. In every ten criminal hirelings, one is dab— an expert, worth double and drawing a double salary. In every twenty criminal hirelings, one is a dragoon— someone occupying two branches of one profession. Takes one and a half share.

When paying for information or for havens, the price is equal to 14x a day's wage for a one-time service to get 1 rumor, opportunity, or favor and 60x a day's wage per month for 1d3+1 each month. Bringing down the heat on an establishment counts as a favor owed to that establishment, and if they roll low enough on the d4 the haven may cut ties or demand a favor of you.

Thieves and Burglars

• Adam Tiler- pickpocket's associate, who runs off with the goods

• Angler- thief who steals with a hooked staff, especially through windows and grates

• Autem Diver- pickpocket who specializes in churches

• Banks's Horse- horse that plays tricks, or a a horse rogue

• Bloss- woman who will pretend to be your wife, as in shoplifting operations

• Boung Nipper- Cutpurse

• Bubber- dine-and-dasher

• Budge- thief who slips into houses and steals clothing

• Bufe Nabber- dog thief

• Bullycock- robber who initiates quarrels to create a pretense for the theft

• Cracksman- house-breaker

• Diver- pickpocket

• Dubber- Lockpicker

• Dunaker- cow thief

• Bulker- pickpocket's accomplice who pushes someone against walls

• File- pickpocket who works with a thug and someone who runs off with the goods

• Fire Prigger- thief who loots burning buildings under the pretense of saving the goods

• Ken Miller- housebreaker

• Knuckle- superior pickpocket who steals pocket-books, watches, etc. in public places

• Lully Trigger- thief who steals wet laundry set out to dry

• Pad Borrower- horse thief

• Poulterer- thief of letters

• Resurrection man- corpse thief

• Robert's man- experienced and mighty thief

• Rusher- thief who bursts into a home to rob it after someone opens the door to speak to them

• Tayle Drawer- sword thief

• Tradesman- general-use thief

Robbers and Killers

• Amuser- robber who throws dust or snuff into the eyes of their targets.

• Ark Ruffan- robber skilled in boarding, known for throwing victims overboard

• Bad Bargain- worthless soldier. Half price

• Brother of the Blade- a soldier

• Bruiser- a boxer

• Clove- general-use rogue

• High Pad- a highwayman, a robber of the barren spaces

• Low Pad- robber who acts on foot

• Freebooter- lawless plunderer

• Hackum- bravo or slasher

• Jumper- robber who enters by the window

• Land Lubber- countryside plunderer

• Miller- murderer

• Picaroon- pirate

• Rapparee- outlaw with a rapier

• Scourer- brute who wanders the streets beating strangers and breaking windows

• Waterpad- riverboat robber

Cheats and Recorders

• Affidavit Man- false witness, giving any report for hire.

• Bene Fearer- counterfeiter of bills

• Elf- fairy or hobgoblin

• Glimmerer- sham beggar with false evidence that their belongings were burned in a fire

• Jarkman- counterfeiter of passes, licenses, and certificates for beggars

• Owler- wool smuggler

• Pincher- short-changer

• Sharper- cheat

Information and Haven

• Abbess- brothel mistress

• Amen Curler- parish clerk

• Arch Rogue- chief of a gang.

• Beggar Maker- ale-house keeper.

• Bluffer- inn-keeper. 

• Flash Ken- home that harbors thieves

• Haberdasher of Pronouns- schoolmaster

• Queer Rooster- eavesdropper who pretends to be asleep to spy on thieves in cellars

Miscellaneous Services

• Bandog- bailiff. Double, or monthly fee to leave alone

• Prescription of Aegrotat- apothecary's note excusing you from chapel

• Barker- announcer skilled in drawing business

• Beak- judge or magistrate. Cannot normally be purchased except by nobility

• Bellwether- mob leader. Cost is double if they must provide the mob

• Black Box- lawyer. Double cost for illegal measures, but courtroom antics are included.

• Brother of the String- a fiddler

• Brother of the Whip- a coachman

• Carrion Hunter- undertaker

• Cat's Paw- general-use accomplice

• Catchfart- footboy

• Catchpole- sheriff's deputy

• Cent Per Cent- usurer

• Chop Church- priest who sells church appointments and other preferments

• Family Man- fence

• Feuterer- dog-keeper

• Glim Jack- linkboy. Also called a mooncurser

• Jack Ketch- hangman. Traditionally paid 13 gp per hanging.

• Impost Taker- gaming-table usurer

• Knight of the Rainbow- footman

• Mute- undertaker's servant

• Nimgiver- physician or surgeon, specializing in venereal diseases

• Quill Driver- scribe

Recreating Prepublished Thief Skills (B/X)

The story I have been told is that the fellow who originally came up with the thief class, Gary Switzer, originally pitched a skill system very different from what made it to official print. Rather than the much-maligned percentile chance to climb sheer surfaces, pick pockets, and so on, a thief simply attained their skills with the progression that a magic-user attained their spells, with varying levels. The main difference of course was that a skill was not expended for the day upon use.

This always seemed interesting to me, so I've decided to try to recreate that here, using a few thoughts of my own for diffent thief skills but largely stealing them from ktrey's list of alternate thief skills I commented on once before. Unfortunately I don't have the OG list Switzer came up with, but I think the result is still strong.

A skill system cannot replace cautious play or save reckless play.

A thief learns follows the magic-user's spell slot progression, learning a 1st-level skill at first level and a new skill each level, gradually selecting from more powerful skill lists. They can practice new skills in the same way a magic-user researches spells, learn from manuals and mentors in the way a magic-user does, and so on. With a week of practice, a thief can switch out skills known into their skill slots, which represent the abilities they're keeping up on and can employ while adventuring.

In general, the effect of a skill should be clear from its name. I will provide parenthetical clarification and advice. This article assumes that a PC is generally competent and can do anything with the right tools and time, so thief skills should go above and beyond that standard.

1st

1. Climb Sheer Surfaces
2. Trap Circumvention
3. Hear Noise (6-in-6 chance)
4. Hide in Shadows (will not be seen if holding still in shadow. Remember, an area with a single light has many shadows)
5. Open Locks (only requires a dagger or similar tool. Takes 1 Turn for good locks, 1 round for shoddy ones. Ineffective against magic locks)
6. Breath Control (among other things, hold your breath for 3 minutes while exerting yourself or 10 while keeping still. Can decline to inhale even when surprised.)
7. Identify/Diagnose Poison (know mechanical effects and any medical recourse. Must see effects or get a waft or something.)
8. Law (among other uses, may ask DM "is there any legal trick I can use to do X?" Learn alien law codes in an hour with a law book. Attain a frightful reputation in any settlement in a week.)
9. Juggling (among other uses, skilled enough to hold three hands'-worth of objects at once)
10. Balance
11. Appraisal (anow value in normal circumstances, always spot a forgery)
12. Contortion (among other things, slip most bonds automatically)

2nd

1. Move Silently (+1-in-6 chance of surprise when you might be spotted, automatic surprise when you can't be.)
2. Find/Remove Traps (6-in-6 chance of discovering when searching an area. Requires the minimum conceivable time and tools)
3. Pick Pockets (can discern what's in a container by brushing past it. Automatically succeeds with plausible objects, but foe can save vs devices to notice 1d4 Turns later.)
4. Mob Agitation (turn a grievance into immediate action. Normal peasants test MOR before participating in deadly violence.)
5. Impersonation
6. Ventriloquism (range 30 feet in normal circumstances, 60 in echoey spaces) 
7. Forgery (only requires a writing implement, paper, and, if copying a specific person, a handwriting sample)
8. Smattering of Language (speak all unrestricted languages with the fluency of a two-semester course. No alignment languages, secret tongues, or dead script)
9. Arson (fires spread 1 room each Turn, or 2 with accelerants. Requires flammable floors or beams, but can greatly damage constructions that are mostly stone.)
10. Snares and Alarms (by default, you're assumed to have string and a few bells. By default, snares catch all unintelligent creatures who pass by and can't free themselves easily, but with better preparation can have stronger effect.)
11. Innuendo (communicate message to specific people without saying it outright)
12. Decryption (at slow reading speed)

3rd

1. Drug Tolerance (still get benefits, if any)
2. Explosives (can manufacture in any village. 50 gold makes a petard, 500 makes enough powder to level a small building or tear the floor out of a ballroom. Other forms are possible. Takes 1 hour of work per 25 gp in cost.)
3. Antidotes and Antivenom (always specific to particular types of poison and venom. Each dose costs 100 gp to manufacture, but in some places the cost may be halved due to the knowledge of herbalists or availability of ingredients. Must be applied within 3 Turns of the affliction, or 1 Turn if deadly.)
4. Double Life (maintain a secret identity. Among other things, can replace most required sleep with disguised socializing and relaxation.)
5. Sapping (with a team, can dig 50 feet in one day. At will, can choose when an undermined wall will collapse.)
6. Camouflage (by default, you're assumed to have the needed supplies. +1-in-6 surprise when traveling through a specifically appropriate area, or automatic surprise when lying in wait.)
7. Propaganda (published or preached criticism always finds purchase, either with the have-nots against the haves or vice-versa)
8. Open Magical Lock (Requires Open Lock skill. only requires a dagger or wand. Takes 1 Turn for good locks, 1 round for shoddy ones. Always works as long as there's a mechanism, even one as simple as a hinge.)
9. Poison Manufacture (can manufacture in any village, forest, or badland. 50 gold makes a contact numbing agent, 500 makes an odorless bane that causes a save vs death when ingested. Other forms are possible. Takes 1 hour of work per 50 gp in cost.)
10. Hide Infravision Signature (Requires Hide In Shadows skill. Will not be seen if holding still in shadow, even thwarting infravision/darkvision)
11. Identify/Diagnose Curse
12. Appraise Magic Item

4th

1. Venom Immunity
2. Poison Immunity
3. Sopoforic Manufacture (can manufacture in any village, forest, or desert. 25 gold makes an inhaled knockout fluid, 250 makes an grey paste that causes a save vs death or fall asleep when introduced to the bloodstream. Other forms are possible. Takes 1 hour of work per 50 gp in cost.)
4. Sense Benevolence
5. Gambling (determine outcome in all games of chance. Once per settlement, may spend a week to win a lot of coin.)
6. Find/Remove Magic Traps (Requires the Find/Remove Traps skill. Detects even when there is no non-magical sign. Deconstructs even when there is no non-magical mechanism.)
7. Smattering of Restricted Language (speak and write all restricted languages with the fluency of a two-semester course-- alignment languages, secret tongues, and dead script)
8. False Death (fake death utterly, even stilling heartbeat. Cannot be made to cry out, cannot be tickled, don't need to blink, etc.)
9. Sincerity (Defeat magical scrying and truth-compelling magic utterly with doublethink that says you really are telling the truth, or that you're not really there, etc.)
10. Echolocation (range 100 feet in normal spaces, limitless in echoey spaces.)
11. Deathtraps (may construct them with minimum conceivable tools and time.)
12. Wall-Running (up to 30 feet)

5th

1. Scroll Use
2. Alchemical Duplication (create potions as a magic-user can)
3. Lie Detection
4. Sense Ambush (and therefore, can't be surprised by them)
5. Bushwhacking (when camping and lying in wait, always get surprise)
6. Diving Dodge (go prone to avoid a ranged attack or beam spell, etc.)
7. Deprogram (Published or preached criticism always finds purchase among the charmed, compelled, indoctrinated, and others who are normally rendered unable to be persuaded.)
8. Radiation/Mutation Immunity
9. Belong (your presence alone is not suspicious except to the inner circle of secure locations)
10. Hypnosis (with a Turn of work, can make someone sleep, make them suggestible, change their habits, implant a trigger, etc. Extended or drastic triggers can be thwarted with a save vs devices. Cannot hypnotize someone into harming themselves directly.)
11. Incite Strike (Requires the Propaganda skill.)
12. Jailbreaking (from the inside. Creates an escape opportunity in 1d6 days unless in solitary confinement or similar.)

6th

1. Cursebreaking (always specific to particular types of curse. Each ritual costs 100 gp to develop, but in some places the cost may be halved due to the knowledge of seers or availability of relics.)
2. Exorcism (takes 1 Turn per HD of the target spirit. Interruption does not foil any progress as long as you can keep chanting.)
3. Magical Law (among other uses, may ask DM "is there any linguistic trick I can use to thwart this magic compulsion?" Understand the effect of combining two forms of magic before it is done. Attain a frightful reputation among fey in a week.)
4. Sense Doom (get a funny feeling before something bad happens to you, not caused by you or your allies)
5. Blast Immunity (requires freedom of movement. Applies to fireballs and most things that require a save vs breath.)
6. Greater Pick Pockets (Requires the Pick Pockets skill. Automatically succeed with any object not in the target's hand or that would require a disassembly process, but foe can save vs devices to notice 1d4 Turns later.)
7. Incite Coup (Requires the Incite Strike skill.)
8. Catch Spell (beads, beams, bolts, etc. Can set down carefully or try to throw back on your turn.)

A Humble Proposal For BX Thief Skills

 If you talk to BX/OSE afficianados, they will justify the maligned thief abilities in a variety of ways, ways that I sort of doubt are totally clear in the text but which nevertheless are the best version of the rules as I see them. They might assign competency to the thief such that they succeed on all basic applications of the skill and only need to roll sometimes, or emphasize the near-supernatural nature of even a level 1 apprentice. Even in this best-articulated framework, it can be tricky to determine how to approach a thief-adjacent activity which is attempted both by thieves and members of more square classes. For instance, if the party is climbing a non-sheer surface under time pressure, how should it be run? For this there are many answers.

But it's sort of weird! Sometimes we say "the thief is better than other classes at certain things," make a procedure for how thieves do it, then improvise from that procedure to determine the worse way the fighter does it. But a lot of these activities are pretty common for an adventure! Maybe the basic procedure should be the non-thief one, and thieves can just get some bonus.

I have a way of doing thief skills that entails more "spot rules" for the thief class, but that I argue may be better integrated into the game procedures in general. For each, I looked at the way a non-thief might do them on the OSE SRD, and assigned a bonus that I thought appropriate.

In coming up with a homebrew rule for thief skills, I am following in the footsteps of many. This proposal is untested, but I think it's a viable direction to take.

This could be you!

* Climb sheer surfaces (CS): A dexterity ability check is required for each 100’ to be climbed, made with a +4 bonus if the climb is any easier than sheer. If the roll fails, the thief falls at the halfway point, suffering falling damage.

[Notes: while ability checks are an optional rule in OSE, the procedure for climbing does in fact call for one, so I thought it would be appropriate to do so here as well.]

* Find or remove treasure traps (TR): When actively searching for traps, the trap’s activation chance is reduced by 1, even reducing traps that always activate to a 5-in-6 chance. An actively searching thief notices when a trap would have triggered.

* Hear noise (HN): In a quiet environment (e.g. not in combat), a thief may attempt to listen at a door or to hear the sounds of something (e.g. a wandering monster) approaching, with pinpoint accuracy on a 2-in-6 chance.

[Notes: this matches the halfling class ability.]

* Hide in shadows (HS): When not directly illuminated, you can remain motionless. No one who knows where you are can detect you from more than 5 feet away until you move or speak.

[Note: this one required more direct innovation. The ability to be unseen as long as one is completely still has come up in several GLoG games, and always requires more creativitiy than one might expect.] 

* Move silently (MS): A thief moving carefully alone gets +2 to their encounter surprise chances. Groups composed entirely of thieves get the same bonus.

* Open locks (OL): Requires thieves’ tools. The thief may make an Open Stuck Doors check on a lock, modified by dex instead of str. If used on a locked door, it does not eliminate the chance of surprise. A thief can only try this once per lock per level.

* Pick pockets (PP): Used against an unaware or friendly target. Make an attack roll, using the +4 backstab bonus if the target is unaware. On a hit, instead of damage take an object that would be feasible to steal, up to a sheathed weapon or worn bracelet. If a particular item is known, the thief can take it. Otherwise, the DM selects a likely object or rolls on a table, such as this:

1. 1d10 silver coins
2. letter from an associate or family member
3. knife
4. Tot of wine or potion
5. ration appropriate to station and climate
6. rat (roll reaction)

[Note: obviously this one also required innovation. Really, how often do PCs pick pockets? It's a high-risk gambit that often has a high penalty for failure, and most foes either carry nothing interesting or are about to die anyway.]

ktrey's Unusual Thief Abilities and Considerations on Niche

 I was playing around with the d100 Unusual Thief Abilities table by the prolific creator ktrey, and thinking about its various uses. The B/X thief abilities existed not only to emulate a particular kind of character but also to define the game they were made for. These early D&D thieves have abilities like "open lock" and "find and remove traps" because those are the abilities that many early D&D games necessitated. If there were no thief class, we might imagine that there would have to be fewer traps and locks in dungeons or that rules would have to be added to allow people to have a mechanical procedure for addressing those challenges in a similar way to how the thief class would.

This reminds me of the later principle called niche protection, the idea that the system of the game should not only give a class certain abilities but ensure that other player characters cannot perform the same category of ability well. While I feel like niche protection became a talking point in the more build-focused style of play that meant people were more likely to feel outshon in play by their friend's meticulously designed character, early D&D certainly has forms of niche protection.

Only a thief gets a procedure to open locks. Only a fighter can use a magic sword. Plenty of considerations like that. One difference is that the game (cum fide) assumes that a PC is competent in all general adventuring practices, and this is actually a great consolation. Even if you don't have the thief's trapfinding ability, at least you don't need to roll a die for every five-foot square you probe with your pole. 

Another difference, it must be said, is that the philosophy of niche protection is not drawn out to its fullest extent in classic D&D. Consider all the reasons that you need a thief to pick a lock but you don't need an elf to find a secret door. I'm not sure that any given edition of classic D&D gets niches exactly right, but it really does feel like a considered design decision.

Finally returning to ktrey's unusual thief abilities table, it sparks my imagination simply because it leads me to think about the games and game systems that would feature them. It's not every campaign where timing fuses or bootlegging is as central as opening locks. I wonder also at how the game is to be played if no PC can pick locks or perform some other typical thief ability. The relationship between a class's abilities and the shape of the system must always persist. and each must be apt for the other.

For your consideration, ktrey's table turned into a table with Spwack's html tool:

GLoG Class: Hepticove (💰)

"Red alert, gang! Turns out that compassion, justice, and singing those church songs actually brings you closer to God. Turns out that we're all a part of God, separated long ago and gradually returning to God by destruction of the ego. Your only shot is to embrace materialism, have lots of beef and wine, and never say the name of God. Then, spend as much money as you can on yourself and your mates.

I wish it wasn't so, but if you want to resist the God-That-Is, you've got to keep it sleeping."

A continuation of the Catching-Harvest campaign pitch.

art by George Cattermole

Hepticove

Requires a fabric crown, a manacle, a knife, a beard, a comb, some clean underwear, and three pieces of swag.

For every level of Hepticove attained, get +1 to saves.

• C: Prominence, Awareness of God, +2 MD
• D: Education, +1 MD

Prominence: When there is injustice, people look to you. At will, you can make yourself the most prominent or least prominent member of a group.

Awareness of God: The top of your head is a special spot. It warns you when God is near. When you chant a drinking song, you can sense the presence and general direction of nearby divinities. You know magic and can study spells. The first time you become a hepticove, you learn two spells from the list below. 

Education: When you send someone to speak for you, they speak with your grace. Both of you make any called-for charisma rolls, and they take the higher. Your students come to you to resolve disputes. You can always cite scripture for your purposes. You can get together a gang of 1d13 disciplines, but they're not exactly reliable.

The Spells (d8)

     1. Ego: gain [sum] temporary HP and Turn spirits of [dice] HD or fewer.

     2. Attachment: resurrect something dead for [dice] or fewer hours that has [sum] intelligence or less.

     3. Lust: track someone by scent for [dice] hours. Get +[sum] to notice details about them but -[sum] to 

     resist their deceptions.

     4. Greed: Know the way to acquire any valuables or other desired objects within [dice]x30 feet.

     5. Anger: for ten minutes, the next [sum] times someone tries to attack you, you get to attack them first.

     6. Injustice: create a reserve of [sum] iniquity points that you an retroactively add to someones' rolls to:

          flee authorities, break bonds, or incite those with evil intent.

     7. Effability: cease all sounds within [sum] feet of you, except blasphemies.

     8. Reality: move something of a size relative to the amount of MD invested up to [dice] miles: 

          1 a sword, 2 a person, 3 a wagon, 4 a city block, 5 a mountain

Mishaps

Whenever you roll doubles on your MD when casting a spell, or whenever you learn a godly spell, save vs. curses or suffer an enlightenment. Roll a d8 and consult the Hepticove spell list. You are unable to express the sin that the rolled spell is named for. If you know that spell, the DM will replace it with some more virtuous spell and you cannot relearn the old power. If you roll a sin you've already lost, lose the top sin on the list that you do possess.

Losing access to any four sins is deemed unplayable, but that's a decision for each table to make. For each oppressive reign of terror or for each saint martyred, you may regain a sin.

Some Swag from the Criminal World

• Really Good Hair of the Dog: imbibe to suppress 1d4 fatigue for five hours. For a hepticove and only a hepticove, you can replace your next MD roll with a d4 or a d8. If you roll a d8 and get a 7, treat it as a 6 and a 1 for the purposes of mishaps. If you get a 8, treat it as a 6 and a 2.
• Ring of Holding: a sharp 9-inch throwing ring that deals 1d6 damage, rolling an extra d6 whenever you roll a 6. While it's sticking out of a person or a fresh corpse, you can reach inside the ring to retrieve or store objects, filling a volume equal to a coffin fit to your exact dimensions.
• Torture Wheel: makes you popular with your subjects. Said to be able to make saints recant their faith, but examples from history are lacking.
• Sword of the Self: dark sabre, in which your reflection stands, always ready to reassure you that you are on the right course. Deals 1d8 damage and confers +1 MD each day.
• Power Box: polished stone ark, perfectly square. Can only be opened by someone who knows what it is. When it is opened, someone who is not present immediately dies. Inside is a new Sin, and a new hepticove spell that can be learned immediately. Engravings on the outside give a clue to the context.
• Pillar of Wisdom: a wooden pole with a little platform at the top. While preaching from the top of this pole, a hepticove may decide the first MD roll they make that day, provided they haven't touched the ground since sunrise.
• Beggar's Shoes: or rather, formerly beggar's shoes.

d10 Unpickable Locks

 Some old-school dungeon modules have the bad habit of including secret doors, unspoken trap mechanisms, unpickable locks, and other keyed items that make sense in a certain game procedure but that lack vital information for understanding them in a fiction-forward game. When I design game elements like these, I ensure I have an idea of how they're supposed to function in the fiction of the game world so I can reliably respond when a player describes interacting with that element. Without knowing that a secret door has some kind of seam or handle or trigger, I can't represent an investigation of the area around that door outside of the Searching For Secret Doors procedure.

In some ways, the problem is worse for a lock that the text deems unpickable. Both the average player and the average DM have little theoretical knowledge of how a lock, modern or medieval, functions. The player doesn't know how to approach a lock from a fiction-forward angle once their lockpicking roll has flatly denied, and if they did a DM likely couldn't elaborate. 

Here I offer ten good-enough justifications for a door to be considered unpickable, that shouldn't be too jarring to apply if you notice at the last minute that it's listed as such in the room description. Since the PC attempting to pick a lock is presumably proficient in doing so, err on the side of telling them all about the mechanism of the lock before them. As it is said, any locking mechanism is also an unlocking mechanism, so these can all be theoretically bypassed with significant effort (which, remember, OSRly is a good thing.) Anything below that would be deemed implausible by a real-world expert is acknowledge and accepted.

d10 Unpickable Locks

1. Picking this lock in the usual way will actually snap a “trap pin” into place, making it impossible to open, even with the key. If you recognize the reinforced ring around the core that thwarts drilling, you might know the trick, lifting certain pins higher than you normally would to avoid triggering the trapped pins.

2. The lock is enchanted to only yield for a key with a matching enchantment. Dispelling the door renders it unopenable for the duration. Arcane thieves and rich city locksmiths could enchant any key or narrow bit of metal to match the lock if they had access to it.

3. The lock has two cores, the hidden second one activated when the other one has turned 30 degrees. This means a prospective picker doesn’t have access to the pins at a time they can apply tension to them.

4. A retracting plate inside the lock prevents a picker from applying pressure while inserting the pick. Its mocking devil face-shape adds insult to injury. This feature is obvious on sight even to someone who hasn’t seen it before.

5. The lock cylinder curves sharply, requiring a key formed from a tight chain. Normal picking tools cannot reach the back of the cylinder. This lock is easy to break, which renders the door inoperable.

6. Additional pins in the side of the cylinder need to slide inward for the lock to turn. The key is magnetic in just the right areas to pull the pins into place. A typical set of lockpicks has no means of pulling these extra pins in, and a thief may not even notice them.

7. The half-circle faced key rotates under a metal plate as it is inserted, in a motion that typical tools cannot replicate. They are prevented from even entering the lock chamber.

8. When the key locks a lock, the last third detaches in the cylinder, lodging it in place and rotating it out of position, making the last few pins inaccessible until the key is reinserted to snap onto the tip, or until or a precise facsimile is manufactured to fish it out

9. The pins of this lock are made from ghost bones, and provide no accurate sense of touch or tension through lockpicks. Accordingly, a thief cannot tell when a pin is in position. A cleric Turns this door as a 2* HD undead, which doesn’t unlock it but renders it pickable. While it is Turned, the key will not work.

10. Two-factor Authorization 😨! What is apparently the locking mechanism of the door is in fact simply a trigger for a spell to telepathically send a unique password to the wizard-smith who designed this lock, which must then be spoken aloud. Dispelling the door renders it unopenable for the duration. A mind reading spell can secure the password as it is sent out.

Outdone in Ingenuity, Skill, Extent of Resources, and Fertility of Invention (💰)

"There is something of the devil in the thief's voice when he boasts, even if his message is nothing but the truth. There is something in the traitor that enflames the heart and lures the mind. Let no one say that the man is peculiarly strong in his passions. If he does not marry for love, he is apt to marry for property; if he is addicted to intoxicating drinks, he is apt to marry for pleasure.

Is it a question of education? 

Yes, education is a great help."
-Arnu, Patricove of Hepton

Thief

Start with a big burlap sack, shoes good for running, lockpicks, a longknife, a mask, a striped shirt (to avoid being spotted), and three random pieces of gear from the Catalog. These are in order of importance.

For every level of Thief attained, get +1 to running away.

• A: Efficient Ratio, Plunder
• B: Society

Efficient Ratio: You can always carry something if you have the inventory slots to carry it. You don't need to specifically get a bag or satchel or backpack beforehand.

Plunder: When you've got a big old sack or a carpet bag, it comes in useful to stow the swag. Get +[level] inventory slots. You can ransack a room before anyone happens upon you, automatically triggering any traps around.

Society:  You are now a "made man" in thief society. You are entitled to sanctuary and have learned thieves' cant. You know where to purchase poison, thief's rope, hits, and the like. You can bring disputes to your local anti-noble to be resolved. Before every adventure, you can get 2d2 loyal-yet-bumbling lackeys who are fearlessly loyal as long as they get their cut. You have nebulous responsibilities to Society now.

The Catalog
1. rocket, shoots 150' before exploding into flames crimson and adamant. Spooks spirits, pulps people, and blows doors off their hinges.
2. grappling hook and 40 feet of silk rope
3. earhorn. When set against a door, an eavesdropper tends to hear the juiciest secrets.
4. black iron crow, Also called a prybar, wrecking bar, or jemmy
5. smoke bombs (4-pak)
6. red-glass bulls-eye lantern (won't ruin nightsight!)
7. oil can. Scentless. Stops a rusted door from squeaking or causes pursuers to trip.
8. telescoping pole (goes out to eleven feet!)
9. climbing shuko and foot spikes (really works!)
10.  Hand of Glory. Light an unburnt digit to cast hold person. (Certified genuine hand!)
11. x-ray goggles. Penetrates two inches. Shows hollow spots in the wall and who has a skeleton.
12. disguise resembling a godparent

from Basileus, by Andrew

A Digression about Lockpicking
Some people don't know this, but learning how to pick locks is easy. With simple tools, some free time, and pointers from another novice you can pick up the skill super fast. Most locks at the tech level of your game are likely simple by modern standards. Many medieval lockpicks were glorified keyrings, since you didn't need precise teeth to seduce a lock. Therefore, you don't get special lockpicking abilities with this class, but it's understood that you can pick locks. Other people can with a ten minute lecture and a practice lock.

A Digression about Thief's Tools
Assembling a full pack of thief's tools is a wonderful goal for a fledgling adventurer of any class. Vital equipment includes a file, lockpicks, mirror, scissors, and pliers. Look also for a hook, pulley, rope, pry bar, hammer, spikes, saw, and lock oil. Since these tools are so various, you can understand why some designers would simply give out blanket "thief kits". Yet, each tool is handy for a variety of adventuring situations, and you're likely to forget you have a file if no one tells you. Collect tools! A handyman's closet is more useful than a jewelry box to an apprentice burglar.

A Digression about Thieves' Cant
This is a cryptic vocabulary. Some words a thiefing jargon, technical terms of differentiation that those of other professions would have no need for. Other words are for very common concepts like "man" or "woman." Canting would do a good job of obscuring the meaning of a sentence like "the apprentice pickpocket drinks the adulterer's alcohol" but a poor job of obscuring "where is the hollandaise sauce?" or "brevity is the soul of wit." The difference between common speech and thief's cant is not as significant as the difference between English and French, but every difference is made to intentionally exclude outsiders to Society. You can't cant every idea, but you can cant some ideas so well that a mark won't be able to tell that any innuendo is going on. Full conversations in cant are seldom desired.

A Digression about Robbery
Some people don't know this, but robbery is easy. (Don't rob people.) In the modern day, the standard method is to pass a bank teller a note telling them that you're robbing them. In the olden days, you would walk up a traveler, brandish a weapon, and tell them that you're robbing them. The risk is not so much that they'll resist you as much as that the authorities will try to capture you later. If a PC is robbing easy targets, treat it like carousing or rumor-mongering-- a down-time activity with a small chance of coming back to bite you. That said, the funds offered up at knifepoint probably really does pale compared to the wealth tied up in treasuries, fortresses, and dungeons, where the guards will actually try to stab anyone who brandishes a snicker-snee at them.

Gameplay Loop: The Catching-Harvest Campaign

Live fast ☞ scope out a mark ☞ burgle ☞ fence the goods ☞ repeat step one

The point, as ever, is to be stinking rich. The problem is that levels are not permanent-- the more extravagant your expenses were last month, the higher your level. You can maintain a level-one existence without risk just by sticking up passers-by, always moving so the law never catches up to you. But if you dream of a full meal and an emptied wineskin, you need to get your hands on real lucre. 

The early game consists of seducing the innkeeper's assistants to have them let you in at night, or sneaking by kept captains to free them of their pensions, maybe digging up the town's latest stiff for their jewels. The mid game involves collaboration, winning the friendship of landladies to get tips on where you can find wealthy travelers, bribing black monks to switch you with a dead body to have you smuggled into the earl's uncle's wake, forming a gang, and beefing with rival flocks. The late game involves clearing out dungeons for hideouts, knocking over the king's treasuries, and buying a modest barony in Zaldo.

This ambition is in danger of getting spoiled by something-- a war, a vampiric usurper, or the dying out of Society crime. The roads are better watched than they used to be. Getting your money at best is getting worse and worse.