A lot of folks have a lot of opinions about what makes for a good, game-able NPC. I’ll try to consolidate the better pieces I’ve found, paraphrase, and synthesize them.
Sources
In How to Create Compelling NPCs in Seconds, Kelsey Dionne (Arcane Library, Shadowdark) suggests that we need one or two standout appearance traits, a physical mannerism, and a secret drawn from convenient small-talk topics F.O.R.D (family, occupation, recreation, dreams).
In People Are Problems: NPCs as Challenge Elements, Dwiz (Knight at the Opera, Brave) suggests that NPCs need a title, value, something they’ll exchange for their value (wants/do-not-wants).
In Mothership 1e, Sean McCoy (Win Conditions) suggests that NPCs need to know what they think with (their head? their fists? their wallet?), what they want (clear, attainable, material), and how the players interact with them (are they powerful or powerless? helpful or unhelpful?)
In The Universal NPC Roleplaying Template, Justin Alexander (The Alexandrian) suggests that we want their appearance, a representative quote, a mannerism, a personality trait, essential context, interesting anecdotes, and key info (clues, value, etc).
The Parley Move in Dungeon World implies that players ought to be able to gain some sort of leverage on NPCs (otherwise they can never Parley).
In The Four Blanks Method of Faction Generation, GFC (dredged from the gyoll, youtube) suggests that a Faction (often represented by a NPC) ought to have a motivation, an obstacle, and a method to surmount that obstacle.
Getting more abstract, Fronts in Dungeon World suggest that every threat has Grim Portents that are followed by an Impending doom. This is very similar to clocks in Blades in the Dark, which is similar (and more abstract) than Justin Alexander’s Activity Logs.
Synthesis
From first principles. RPGs are a conversation, and so we need information to facilitate that conversation. Talking to a NPC in a RPG is therefore a conversation about a conversation (the same way that your character climbing a tree is a conversation about climbing). Different tables zoom in at different levels.
At Dwig’s table, for example, much of that conversation seems like it takes place at a high level. I imagine he says stuff like “You chat with the blacksmith and he reveals that he’s running short on metal, and will give you his grandfather’s mithril chain ya’ll can fetch some iron from the Dwarves’ mine.”
Justin Alexander, on the other hand, might go much more in depth, like:
GM: You’re introduced to Warwick, the town’s Smith. He’s burly and visibly stressed. You notice that the forges are cold, and that there’s hardly anything for sale. He says “‘Ello. Welcome to Brandonsford. What can I do for you?” What do you do?
Player: I ask if he has any shortswords available for purchase.
GM: “I did not too long ago, before the dragon came. Haven’t seen the dwarven miners lately, and all of the merchants are too scared to bring me metal too, so I don’t have anything to work with. Tell you what - if you can bring me a shipment of metal from those mines the dwarves were working, you can have my pappy’s mithril shirt.”
etc.
In real life, conversations tend to be either smalltalk or goal-oriented (or both). Most people find it jarring to go straight to goal-oriented talk without any small-talk first. NPCs should act similarly, so if you want to have them talk directly it’s good to have them mention something about their family, occupation, recreation, or dreams before they get to business.
“Son’s been practicing his archery, dang kid still can’t hit the barn but he’s tryin”.
“Well I’ll tell ya, smithing is hot and loud, but it’s honest work.”
“I’ve been cooling off in the evening by takin a dip in Farmer Gill’s pond. Nothin beats it.”
“I’d love to get a new roof for the smithy, current one leaks during the bad storms.”
It’s good to be able to improvise these, and so I don’t think they need to be written down. I find it easier to improvise if I know their title and a couple traits. If this is a less focal NPC, something along the lines of “after exchanging pleasantries…” works totally fine to hand-wave the smalltalk.
Then, the players are going to try to get something out of them, so you need to know what they exchange. Important is that both sides can be offering negatives. “I won’t call the town guard if you stop harassing the patrons” is an exchange of negatives.
In order to reason about their exchanges, the most useful and concise format I’ve found is GFC’s. Warwick wants to forge metal in his smithy, but he’s out of metal and the Dwarves haven’t brought him any more from their mine in a while. So, he’ll offer his Grandpa’s mithril shirt to any adventurer that can fetch him some.
Per Sean McCoy, it’s good to have these motivations and methods to be specific, attainable, and material. "I want metal from the mines” is a whole lot easier to run than “I want to repair my broken marriage”. If the module (or your own adventure) has Vague, Amorphous, Pie in the sky, Irrelevant, or Delayed goals, rewrite them!
So transform something like “I want to repair my broken marriage” into “I want to forge my wife a new ornamental teapot” or “I want saffron to cook my wife a special birthday meal”. These are things the players can actually help with, and are steps on the path to the larger, vague goal.
That’s also how we synthesize fronts, clocks, and the activity log. You can get away with 1 goal, but GFC’s method gives you two. If you need a more complex faction or NPC than this, you can make the problems recursive. For instance: “I want to secure the town of Brandonsford, but there’s a dragon assailing it, so I’m going to poison the dragon with the faun’s special tree sap, but the fauns jealously guard the tree sap, so I’m going to collect sentimental items that they value for barter.”
If this was Dungeon World, it would look like a Front where the Grim Portents are “Collects Ingrid’s Love Letters”, “Exchanges Love Letters for the Faun’s Tree Sap”, and “Defeats the Dragon using the Tree Sap”, and “Memorialized as the Second Heroes of Brandonsford”.
If it’s Blades in the Dark, same thing but there’s a clock with 4 sections getting filled.
Putting it All Together
This is why Warwick in Brandonsford works.
You’re given what you need to know to run smalltalk (blacksmith, burly, simple, superstitious), he has specific, material goals, obstacles for those goals, and methods to surmount those obstacles.
It’s also why George the Hunter is harder to run:
We know how to run smalltalk (hunter, wild, stone-faced, hopeless), but he doesn’t have a clear, material goal. As written, it’s not clear if or why he would tell the PCs what he knows about the Dragon’s lair or it’s defenses. He’s hopeless!
When I ran George, I made him vengeful instead of hopeless. He wants the Dragon dead because it killed his friends and took his arm, but he can’t physically help. So, he’ll accompany the PCs when they’re ready and show them to the cave and tell them of the black scales. It’s a small change, but an impactful one.
Example From Film
For a masterclass of this, watch literally any Coen movie.
Thanks for reading!
Also, curious to hear what folks think are exemplary NPC descriptions from modules they’ve read/ran. Hit me with them! I need more sources!
Some advice from an old-school AD&D second edition player from the 80s.
I found that giving players a secondary objective helped. Keep everyone involved.
For an important NPC or useful rather, I would hand a chosen person a note with that NPC information and objectives on it and when the moment came, I merely had to look at that person they would catch on and take over.
This worked well for intelligent, complicated monsters as well, allowing the player to choose for the monster and choose for themselves simultaneously .
This was also a great chance for role-playing as a player controlling a monster and their own character at the same time will face complicated choices that affect not only themselves, but the whole party .
One practical thing I like to do is put a three to five word blurb summarizing the NPC right next to their name: Amille Sarsis, Thrill-Seeking Burglar or Ketah Merkton, Religious Laborer. The blurb distills and triggers the prep, almost like a mnemonic. I can fall back on the rest of the template if I get lost. The blurb also provides a handy test for the NPC's design. If the blurb's not memorable, the NPC probably isn't either.