18 July 2017

Simple(ish) Social interaction for d20

The next time I run a d20-based game, I'm going to try this relatively simple social hack my partner and I came up with for players interacting with NPCs. This system should work with just about any d20-based system. The examples below are based on Moldvay B/X and compatibles, but with a little modification should work with AD&D, 3E/Pathfinder, 4E, 5E, and so on.

  1. Referee first determines the disposition of the NPC or group of NPCs (target) the players want to interact with. This is done with a standard 2d6 reaction roll.
  2. Presuming parley is possible, the referee generates a Coercion/Persuasion spectrum for the target by rolling 3d6, and using the modifier determination method for their system. Negative modifiers represent susceptibility to coercion, and positive modifiers represent susceptibility to persuasion. An example using the Moldvay Basic rules:
  3. ScoreSpectrum
    3+3 Coercion / -3 Persuasion
    4-5+2 Coercion / -2 Persuasion
    6-8+1 Coercion / -1 Persuasion
    9-12No susceptibility
    13-15+1 Persuasion / -1 Coercion
    16-17+2 Persuasion / -2 Coercion
    18+3 Persuasion / -3 Coercion
  4. Players desiring something from the target then attempts to convince the target to provide what the player wants by either using coercion or persuasion. The player states the method (coerce or persuade), and gives a general explanation of the action the character takes.
  5. The referee determines the appropriate ability (if any) that might apply, and the player rolls a d20 vs the Moldvay Basic rules combat table (reproduced below; p.B27), applying the bonus/penalty as determined by their choice of coercion or persuasion, plus any relevant ability modifier. Note that this table should be used even if the players are using the Expert rules to keep such interactions challenging for higher level characters. The disposition number becomes the armor class number on the table. Any results higher than 9 are treated as 9, and results lower than 2 are treated as 2, just to keep things simple.
  6. CharacterDisposition roll
    Level9+8765432 -
  7.  If the d20 roll +/- spectrum modifier +/- ability modifier (if any) is equal to or greater than the number on the table, the target will (perhaps grudgingly) acquiesce.
  8. If the players simply want to alter the disposition of the target, they can attempt it by following the same procedure. On a success, the disposition score improves by 1 (up to a maximum of 12).
There is room to tinker here beyond simply adapting for a particular ruleset; some possibilities:
  • One could extend the disposition roll out on either end instead of compressing the high and low ranges,
  • The referee could invert the disposition number if the players attempt to improve the disposition of the target, requiring a harder roll to improve it,
  • Results don't necessarily need to be binary - it should be easy for a referee to incorporate degrees of success or failure based on the roll's proximity to the target number, 
  • The referee could instead use a fixed target number for specific actions.
Credit goes to The Discordian for the initial idea and helping me hash it out, and to the BreeYark article How to Use a B/X Combat Matrix for Everything for the (brilliantly simple) idea of using the Basic Combat Matrix.