A model contains reusable rooms. Each instance binds its variable and exit names to those of the scenario.

This scenario opens the model, lets the player heal, then returns to the calling room's choices.

title: Infirmary
vars:
  hp: 10
models:
  healing:
    variables:
      health: 0
    rooms:
      - id: sheet
        text: 'Health: v_health_v'
        auto_refresh: true
        actions:
          - verb: heal
            target: all
            button: Heal
            do: health + 5
        choices:
          - button: Leave
            to: end_model
rooms:
  - id: start
    text: You enter the infirmary.
    models:
      - model: healing
        variables:
          health: hp
    choices:
      - button: Finish
        to: victory

The models: definitions are keyed by name, here healing. The start room contains a list of instances: model: healing selects the definition and health: hp binds its generic variable to hp, declared in the scenario.

Internal rooms receive a prefix to avoid ID collisions. end_model resumes after the model: here, the Finish choice becomes available. A generic exit declared in exits: can also be bound to a scenario room in the instance.

A model can declare generic lists and collections. Bind them to scenario data in the instance, without copying:

lists:
  products: world.shop.bag
collections:
  hero: world.state

Targets must exist. Paths cross collections only, without list indices. Required properties are checked when a parent is replaced or a saved game is resumed.

See Lists and collections, Tags and Events.