From world rules to player actions

Prerequisites

A world description helps design a game when it leads to actions and consequences. Start with one rule that players can notice, use and test. A world idea and a simple plan of a playable situation are enough; no engine is needed yet.

The principle

A world can have an unusual history, culture and appearance. For a playable situation, establish what these change about the available actions. If cities run on magic, specify what players do with it, what they pay and what happens after they use it.

Yaropolk Rash, known as Yarr Rash and the creator of World-First Method, examines the connection between a world and the possibilities for its first game in The Iconic IP Guide. This lesson draws on the idea in PDF pages 32–39 of the Russian v3.2 edition. The example and verification procedure below were developed for this lesson.

This approach is useful when a world’s distinctive features should inform player decisions. You can also start with an existing mechanic: check which world rules explain its possibilities and limits. One situation is enough for an initial prototype.

From a premise to a choice

Write a short chain:

World rule → player action → changed situation → next choice

Name an observable result for each step. “Magic is dangerous” does not yet define behaviour. “A spell opens a door but draws a guard to the source of its sound” allows a choice of route, timing and location.

Specify the action’s cost separately: a consumable item, time, revealing a position or giving up another route. Add a cost where you want a decision. A decorative detail does not have to become a mechanic.

Practical example

Sound-powered gates

This is an illustrative teaching scenario. In a city, ringing powers machinery. A courtyard contains gates, two bells and a guard. Both bells can be heard at the gates; ringing either opens them for the rest of the attempt. The guard hears the same sound and walks toward its source.

Players can approach the bell beside the gates and ring it by hand. They keep their stone, but the guard heads toward the place they have just occupied. Alternatively, they can throw their only stone from cover at the distant bell, draw the guard away and approach the gates. The thrown stone cannot be recovered until the attempt restarts.

One world property connects opening a route, enemy behaviour and item consumption. The city’s history, other energy types and a trading system are unnecessary for testing that connection. Which options prove useful depends on distances, guard speed and cover; the prototype must investigate those details.

What to keep in the prototype

Choose the details needed to test the intended decision. This example requires a courtyard, two bells, gates, a guard and one stone. Tokens on a plan can represent them initially.

Before testing, define throwing range, movement order and the detection condition. Keep those rules consistent across attempts. Prepare two starting guard positions to see whether players consider the situation when choosing a sound source.

After introducing the rule, ask players to indicate where the guard will go and what will happen to the gates before they act. Then let them cross the courtyard and record their choice, outcome and any hints they needed. If their prediction is correct but they cannot get through, examine execution separately: there may be insufficient time to manoeuvre even when the rule is clear.

Common mistakes

• A distinctive feature exists only in the description: players cannot use it.
• A rule changes to serve a scene: the same ringing produces different results without explanation.
• The entire imagined universe enters the prototype: testing one decision keeps getting postponed.
• Approval of the idea is treated as validation: what the person understood and did remains unknown.

Verify it

• Players have an action through which they encounter the world rule.
• The action has observable consequences that affect the next opportunity.
• Limits are consistent; exceptions can be noticed and explained.
• Every prototype detail has a stated role in the situation being tested.
• The designer’s expectations are recorded separately from player observations.

Prompt for an AI agent

Take one rule from my game world and propose two situations in which it changes player actions. Choose one for a small prototype. Describe actions, consequences, limits and a way to test understanding of the rule. Identify details that can wait. List assumptions and questions that need my decision separately; do not invent playtest results.

Use Scope and a testable prototype to bound the work. Review coherence with the World and Unification lenses.