Social encounters in D&D work nicely--you can model them at the table by talking to each other. You don't need a rule system to know how to talk, negotiate, or make threats.
This is a very different from combat, which can't be emulated at the table (unless you are prepared to crawl over your minis and wrestle your DM), which is why combat requires a robust system of resolution.
However . . .
I still think there is a place for social challenges, specifically for cases that involve (a) an extended persuasion attempt against (b) who must be convinced on multiple points. These types of social challenges sometimes feel too complex to be resolved with a single conversation--there are too many small considerations, and a single DM ruling can feel arbitrary. A formal system for resolution can allow for a numeric description of progress and can add legitimacy to what might otherwise feel like DM fiat.
This is a rather narrow scope, and that's okay. I can expand it later.
Across different systems, combat is usually broken up into a pattern that is repeated every round.
1. We consider the state of the system. How much health do we have? How tough is this vampire? How many potions do I have left? Can I trick the vampire into the sunlight?
2. We make decisions based on that information and roll some dice to determine the outcome.
3. The DM describes the results of the dice rolls, then the series repeats. A player loses 8 hit points. A goblin dies. A spell is expended.
This cycle of information gathering followed by decision making is the beating heart of an RPG--any RPG.
You formulate a plan, act on that plan and then (and this is important) change your plan if it does not seem to be working. The status of your combatant (and thereby your chance of success) is calculated through discrete factors like hit points, which are important for players to know, in order to make decisions and schemes. (This is true even if enemy HP is given ambiguously, e.g. "the goblin appears to be almost dead".)
Good rules for a social challenge should be designed according to similar considerations.
|painting of Vercingetorix by Lionel Royer|
You are trying to persuade an NPC.
The NPC has Patience. Every round that you stay in the social challenge, you risk depleting it further. Once Patience reaches zero, the NPC has run out of patience and you have lost. Patience is comparable to player HP.
The NPC has Opposition. Every round that you stay in the social challenge, you have the chance to make arguments, which will deplete your opponent's Opposition. Once Opposition reaches zero, the NPC acquiesces and you have won. Opposition is comparable to monster HP.
After each round of the social challenge, the players have the opportunity to assess how things are going and choose what argument they want to use going forward. You can decide whether you want to communicate the two scores to your players directly ("The dwarven king has 3 Patience remaining.") or obliquely ("The dwarven king is tapping his foot, looking annoyed.")
I'm lean towards a full disclosure of the two numbers, since more information helps players make better decisions. (It's about as realistic as a player knowing their own HP total, and besides, humans are already decent at determining if they are persuading someone or merely annoying them.)
The Social Interval
An exploration turn is 10 minutes, a combat round is 10 seconds, and a social interval takes as long as it has to.
Every interval follows the same basic cycle as combat.
1. The characters are free to attempt to gain more information. If you walk away from a negotiation and then return later, expect to pick up right where you left off, albeit with 1d4 less Patience ("Didn't we already settle this?").
2. The characters are free to make their argument/offer/threat. The DM decides how likely the argument is to succeed, then tells the players to make their roll. Automatic successes and failures are common. If the players have helped the dwarven king in the past, reminding him of their previous loyalty will soften his position--the only question is how much. Similarly, everyone likes gifts, and everyone hates to be insulted. Use your common sense.
3. The players make the roll. The DM informs the players of their odds before the roll, as well as her reasoning. ("I figure goblins are easy to intimidate, so you succeed with a 14 or less.)
4. If the persuasion succeeds, Opposition is reduced by 1d6 points. If the persuasion fails, Patience is reduced by 1d6 points. The die size can be adjusted up or down as you please, but something must be reduced every turn.
Roleplay every step.
An important part of this is the actual persuasion roll, in step 3. The chance of success is based on the argument put forward, not on external factors, such as how much the NPC personally likes you, or your high Charisma.
Those types of external factors will affect how much Patience the NPC starts with, but once negotiation begins, they no longer play a part. The queen will listen to her lover's propositions all night, but if none of them have any merit, she will agree to nothing.
Setting the Persuasion Roll
At it's heart, this is the NPC asking the players "Why should I do as you say?"
If something is certain to have an impact, it's automatic success. If it is something that the NPC absolutely doesn't care about, it automatically fails. If its something that you can imagine going either way, then you need to set a Persuasion that the players need to roll under.
Follow your heart on this. A decent argument should have a decent shot: a 10-in-20 chance.
There is potentially an asymmetry to the information here. You know your NPC, and the players don't. They can potentially investigate their target before negotiating with them, but even if this step is neglected (an ambush), they can still learn about the NPC through conversation, or by observing how the NPC reacts to their earlier Persuasion attempts.
Setting Up the NPC
You should already know some facts about your NPC. You should know (and have written down somewhere)
- their desires and goals
- their fears and shames
- their values and agenda
- their personal friends and enemies
- their supporters and opponents (if political)
If you don't have anything decided for your dwarven king, you can always fall back on the generic.
Setting Up the Patience Score
This is where personal appeal (rather than rational appeal) comes in.
Patience begins at 6 points, and is adjusted up and down according to circumstances. There are three factors, which are usually worth not more than +/- 2 points each.
Friendship is worth a couple of points. Proven loyalty is worth is a few more. If they frown as soon as they see you, reduce Patience by a few points.
The approach is important. This is where players can make personal appeals, and where they can use their abilities to gain an ear. A Charisma roll is the traditional way to open a negotiation, but other stats can be used, and even cultural elements (such as invoking an ancient right of parley).
When and Where
There is a bad time for everything. An appropriate venue helps, while walking up to the king before he's had breakfast is worth a penalty.
Setting Up the Opposition Score
This is how much the NPC would rather say "no".
Opposition begins at 10 points, and is adjusted up and down according to circumstances. This is a guideline, and when deciding how to adjust it, be sure to consider the following things.
Cultural Taboos. The fun thing about taboos is that they often have exceptions. If no one is allowed in the Royal Crypts except priests, one of the PCs might want to become a priest before they ask the king for access to the Royal Crypts.
Pride/Shame. There's a lot to be gained if you can phrase your request in a way that saves face for whoever you are asking. No one likes to be humbled.
Direct Cost. A resource that is immediately lost. Money, items, troops, etc. These are usually pretty obvious.
Indirect Cost. A linked resource that is spent. Popularity, allies, patronage, risks, etc. Allowing you into the Royal Crypts might anger the Imperial Cult, and that will have knock-on effects for the king down the line.
Opportunity Cost. It might not cost the king anything to let you marry his daughter, but if he does, then he loses the opportunity to wed her to some other prince. He loses the opportunity for a political marriage down the line.
It's not hard to make variations of this. Anything that is a multistep process where each step holds an ambiguous amount of progress. If you don't want a "ticking clock" that indicates failure, use only one progress score. Candidates:
Building a castle. Progress vs Money (which depletes in a mostly-fixed rate each interval).
Researching a new spell. Progress vs Danger. A crude proto-spell is available at 50% Progress, representing a partial success in your spell breeding program.
Navigating a trackless waste. Progress vs Supplies (which depletes in a mostly-fixed rate each interval).
Killing a Zondervoze. A zondervoze is roughly described a city-spirit, composed of a large chunk of a city's population, which function as the zondervoze's "cells" without being aware of their role. A single progress track might be appropriate here--every mass killing or deculturation event will bring a Zondervoze closer to death. You'll attract its full attention from the first event, so there is no competing progress track for failure, since it will be trying to kill you at every turn.
The Heart of the Matter
Essentially any complex task can be broken down into 1 or 2 progress scores.
First archetype: a single progress score that you attempt to increase. Each attempt (or time interval) brings a cost.
Second archetype: a pair of dueling progress scores. Fulfilling the first one generates success, while the fulfilling the second generates failure.
You can layer a thousand complications on these simple constructs (and a thousand RPGs have done exactly that). But I honestly believe that this is the beating heart of most tabletop RPGs.