---
key: practice/one-rule-two-worlds
type: practice
id: one-rule-two-worlds
lang: en
title: 'One rule, two games'
summary: Trace how a small rule change alters player behaviour.
updatedAt: '2026-10-20'
status: active
url: 'https://gamemechanics.pro/en/knowledge/practice/one-rule-two-worlds/'
jsonUrl: >-
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markdownUrl: 'https://gamemechanics.pro/content/knowledge/en/practice/one-rule-two-worlds.md'
aliases: []
tags:
  - Choice and rules
sourceIds:
  - source-3e6c21889ae768e0
  - source-6f794a271cd60b9c
sources:
  - id: source-3e6c21889ae768e0
    title: 'Challenges for Game Designers: author website'
    url: 'https://designgames.wordpress.com/'
    verifiedAt: null
  - id: source-6f794a271cd60b9c
    title: 'Challenges for Game Designers: table of contents'
    url: 'https://designgames.wordpress.com/toc/'
    verifiedAt: null
relations:
  - type: uses
    direction: outgoing
    label: Sources in the selection
    key: resource/challenges-for-game-designers
    title: Challenges for Game Designers
    url: >-
      https://gamemechanics.pro/en/resources/#resource-challenges-for-game-designers
    jsonUrl: >-
      https://gamemechanics.pro/api/v1/knowledge/en/resource/challenges-for-game-designers.json
    markdownUrl: >-
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placements:
  - title: In the original collection
    url: 'https://gamemechanics.pro/en/practice/#one-rule-two-worlds'
supersededBy: []
attributes:
  topic: choice
  level: beginner
  minutes: 40
endsAt: null
provenance: >-
  Thematic inspiration: Challenges for Game Designers by Brenda Brathwaite and
  Ian Schreiber. These scenarios, constraints and checks are independently
  written around broad game-design learning topics. This is not a translation or
  a sequential retelling of the book exercises.
license: CC-BY-4.0
codeLicense: MIT
attribution: gamemechanics.pro contributors
---
# One rule, two games

id: one-rule-two-worlds
type: practice
key: practice/one-rule-two-worlds
lang: en
status: active
url: https://gamemechanics.pro/en/knowledge/practice/one-rule-two-worlds/

Trace how a small rule change alters player behaviour.

## Goal

Trace how a small rule change alters player behaviour.

## Scenario and materials

Create a small game about collecting samples on an island. In version A, players earn points for delivered samples. In version B, change just one scoring rule to reward a different behaviour, such as distributing finds between participants.

Cards and a board

## Constraints

- Keep the board, actions, turn count and starting resources identical in both versions.
- Change only one reward rule.
- Do not add items or abilities.

## Steps

1. Write down the behaviour you want each version to encourage.
2. Play both versions from the same starting setup.
3. Compare routes and decisions. If behaviour stays the same, adjust the reward.

## Deliverable

Two rule sets with the difference highlighted and a turn-by-turn table of player decisions.

## Check your work

- Exactly one rule has changed.
- Expected and observed behaviour are recorded separately.
- Explain why the reward changes decisions, or why it had no effect.

## Reflect

Which incentive mattered most: points, a limited resource or another player's actions?

## Connected materials

- Sources in the selection: [Challenges for Game Designers](https://gamemechanics.pro/en/resources/#resource-challenges-for-game-designers) (key: resource/challenges-for-game-designers)

## Sources and provenance

Thematic inspiration: Challenges for Game Designers by Brenda Brathwaite and Ian Schreiber. These scenarios, constraints and checks are independently written around broad game-design learning topics. This is not a translation or a sequential retelling of the book exercises.

- [Challenges for Game Designers: author website](https://designgames.wordpress.com/) (id: source-3e6c21889ae768e0)
- [Challenges for Game Designers: table of contents](https://designgames.wordpress.com/toc/) (id: source-6f794a271cd60b9c)

CC-BY-4.0 · gamemechanics.pro contributors