Worldbuilding is about “building” a “world” on a macro and micro scale, in rich detail. The technique comes from (sci-fi and fantasy) storytelling and role-playing games, where the authors create whole fictional universes in which many stories can happen. In futuring, and specifically incasting, worldbuilding can add new dimensions to a scenario, like adding colour to a black-and-white movie. Worldbuilding is about fleshing out the scenario into a fully-fledged 'world', populated with cultures and events, maps of places and landscapes. This exercise can take from 15 minutes to months or years, depending on the world-building purpose.
A skeletal scenario or another type of sketch that came out of a visioning exercise should exist before beginning this exercise. Worldbuilding can be done in a workshop, or it can be a writing and visualising exercise that can continue online after the workshop. It can also be outsourced to writers or game designers beyond the group, or people who are a part of the facilitation team. The complexity and richness of the worlds will depend on the needs of the group, as well as the time and resources available. The process described here is for a minimal worldbuilding exercise that can be done in a workshop with the participants. The exercise can take from 30 minutes to several days.