NPC Types (Advanced)

Schema

{
  "npcTypes": {
    "<key>": {
      "name": "string",
      "vulnerabilities": [
        "string"
      ],
      "resistances": [
        "string"
      ],
      "immunities": [
        "string"
      ],
      "description": "string"
    }
  }
}

Example

{
  "character": {
    "name": "character",
    "vulnerabilities": [],
    "resistances": [],
    "immunities": [],
    "description": "A mortal being - human, elf, dwarf, or other standard species. Standard damage, social, and effect rules apply."
  },
  "humanoid_enemy": {
    "name": "humanoid_enemy",
    "vulnerabilities": ["persuasion", "intimidation", "deception"],
    "resistances": [],
    "immunities": [],
    "description": "Mortal adversaries - bandits, rogue soldiers, corrupt officials. Fully subject to social manipulation and fear. Standard combat tactics apply. Can be talked down, bribed, or scared off."
  },
  "undead_shambling": {
    "name": "undead_shambling",
    "vulnerabilities": ["holy magic", "fire"],
    "resistances": ["slashing", "bludgeoning"],
    "immunities": ["intimidation", "persuasion", "deception", "medicine"],
    "description": "Mindless undead - skeletons, zombies, revenants without will. Immune to social effects and fear. Vulnerable to consecrated attacks and fire. Cannot be reasoned with or bargained with."
  },
  "humanoid_cultist": {
    "name": "humanoid_cultist",
    "vulnerabilities": ["arcana", "insight"],
    "resistances": ["persuasion"],
    "immunities": ["intimidation"],
    "description": "Devoted fanatics. Their belief makes them immune to fear and resistant to conventional persuasion. Arcane knowledge can exploit gaps in their ritual understanding; Insight can expose internal doubts."
  }
}

Fields

description

description - baseline behavior summary: how this creature type behaves socially and in combat, what motivates it, and how it perceives the player. This is the template the narrator applies to every NPC of this type before the individual NPC’s basicInfo supplements it.

📋

Note (npcType.description as a generateNPCDetails instruction channel): Because npcType.description is read by the narrator during generateNPCDetails , it functions as an instruction channel for that task across every NPC of the type. Directives embedded in the description — such as formatting rules, required detail categories, or generation constraints — apply consistently to all NPCs of that type without repeating them in each individual NPC’s basicInfo. This is additive to the behavioral template role: the same field can describe how the type behaves and instruct how its detail generation should be structured.

Behaviour

When to create a type

Create an NPC type only when:

• Multiple NPCs share the same damage profile (vulnerabilities / resistances / immunities), or
• The type represents a species, creature category, or profession that more than one NPC will inhabit

No baseline type is required. A world where every NPC is a unique individual (no shared damage profiles) is fine with zero npcTypes entries and type: "" on every NPC. The section is optional.

Damage multipliers

Damage type inheritance

An NPC with type: "goblin" looks up npcTypes.goblin and receives the union of the type’s damage arrays plus its own:

• effective vulnerabilities = npcType.vulnerabilities ∪ npc.vulnerabilities
• effective resistances = npcType.resistances ∪ npc.resistances
• effective immunities = npcType.immunities ∪ npc.immunities

NPCs with type: "" use only their own arrays — no inheritance happens. Use a typed NPC for shared damage profiles, and a typeless NPC when a one-off character needs a unique profile.

Resistance stacking

Multiple resistances against the same damage type multiply rather than add. A 0.5x resistance from the npcType combined with a 0.5x resistance on the NPC itself equals 0.5 × 0.5 = 0.25x total damage taken (75% reduction). The same multiplicative rule applies to vulnerabilities and immunities.

🐛

Common mistake: Values in vulnerabilities, resistances, and immunities must match strings verbatim from combatSettings.damageTypes. Approximate matches do not work — "poison" is not valid if "poisoning" is in the list; "frost" is not valid if only "ice" is defined. Always copy the exact strings from your damageTypes list. Entries that don’t match are silently ignored.

Species ability inheritance

When you define a creature species as both an npcType (so NPCs can be assigned to it via type) and a trait (so players can choose it at character creation), the species trait should include 3 abilities representing that species’ innate capabilities. NPCs assigned that type should also have those same 3 abilities in their abilities array. This keeps species mechanics consistent between player and NPC versions of the same species - a player Elf and an NPC Elf both have access to the same innate abilities.

For guidance on populating vulnerabilities/resistances/immunities see Authoring Guide > NPC Types.

Authoring tips

NPC Types - Vulnerabilities, Resistances, Immunities

The vulnerabilities, resistances, and immunities arrays on npcTypes are matched by the AI against two specific vocabularies during combat and challenge resolution:

1. The skill names defined in your world’s skills collection.
2. The damage type strings listed in combatSettings.damageTypes.

The AI cannot infer custom categories. A value like "blade combat" or "ranged combat" will not match anything unless those exact strings exist as skill names or damage types — the matching is literal, not semantic. Populate these arrays with values that already exist in your skills or damage types, or the arrays will have no mechanical effect.

How you stock those skills/damage types is entirely a world-design choice. A high-fantasy scenario will use a different skill vocabulary than a modern slice-of-life world, which uses a different one than a sci-fi or superhero scenario. Build the skill set that fits your scenario’s genre first, then design NPC type vulnerabilities/resistances around it.

Example: a D&D-flavored fantasy skill set (illustrative — not the recommended default, just one workable configuration among many):

A modern slice-of-life world might leave these arrays empty entirely (combat is rare or absent) or carry social vulnerabilities — e.g. a celebrity NPC vulnerable to social_media, resistant to intimidation. A sci-fi world might have a cybernetic_soldier type vulnerable to hacking and resistant to kinetic. The pattern is the same; the vocabulary changes with the genre.