As an alternative to pre-fabricated game worlds (whether published or home-brewed), I'd like to create some rules for generating a game world gradually and organically.

It would work in a manner analogous to the "fog of war" in some strategy games. As player knowledge of the world expands, either through direct exploration or knowledge checks, details come into existence.

How is this different from any GM who just makes it up as they go along? Because I'd like some sort of pre-established rules mechanic for generating new countries, cultures, geography, etc. This mechanic would be based on part on player decisions, in part on GM decisions, and in part on randomness.

Has anyone ever published a rules set for world creation like this? I'm thinking in terms of a fantasy setting, but I'm open to all genres for suggestions.

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    \$\begingroup\$ Microscope (lamemage.com) has rules for generating an entire universe collaboratively with players at the table. It might be a good place to start, but doesn't really work with "while we're playing the game, let's make the world". \$\endgroup\$
    – Cthos
    Commented May 30, 2012 at 21:12
  • \$\begingroup\$ This is a comment rather than an answer because I'm not sure of the details, but one of the FATE based settings has rules for cooperative star system creation between players and the GM. Would that be the kind of thing you were after? \$\endgroup\$
    – Wibbs
    Commented May 30, 2012 at 21:12
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    \$\begingroup\$ There's another answer I want to give based on the random generators old-school players use to flesh out hex-map-based sandboxes, but it would mean cobbling together multiple tools, not just pointed to a pre-compiled set of tables, so I'm putting it off… \$\endgroup\$ Commented May 31, 2012 at 17:08
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    \$\begingroup\$ You should look at the Wise skills from Burning Wheel. \$\endgroup\$
    – Daenyth
    Commented May 31, 2012 at 20:12
  • 1
    \$\begingroup\$ I cannot tell which direction to go in making a recommendation. It would be helpful to know the OP's desired genre, historical age or tech level, and group gameplay approach (front-loaded GM sandbox supported by rangen details? GM-less totally random sandbox? Group collaborative construction?) \$\endgroup\$
    – As If
    Commented Mar 7, 2014 at 5:07

4 Answers 4


In Mystic Empyrean the players create the world as they explore it with a mix of individual authority, shared authority, and random card draws. It's non-traditional in a lot of ways though, so not everyone's cup of tea. It is definitely a worthwhile example of how such a system could be built. Studying the interplay between the system mechanics, character mechanics, world-generation mechanics, and setting conceits to determine how it ticks could be enlightening.

Key to the on-the-fly world generation are the game's authority structure and the nature of the setting and characters.

Authority is shared by all players:

  • Everyone has a character and GM duties rotate each encounter round.
  • Everyone has opportunities to declare or randomly generate what the group encounters next.
  • Important facets of the world and game are divided up and "owned" by different players so that players can appeal to an authority and so players can contribute in ways they enjoy. Different groups will divide things differently, so some might share creating all new realms and NPCs, or one player might enjoy making NPCs and "own" NPC creation, or one player may own a story arc, or each new realm will be created and owned by a different player, or some other division of ownership.

The nature of the setting is specific but also not particular:

  • The characters are mutable immortals whose personality determines their nature, appearance, and powers. Personality is challenged and changed by play, influencing nature/appearance/power.
  • The world is multi-faceted, with many different realms with vastly different physics and realities all in one shared "multiverse" that the PCs can cross between.
  • All realms but the starting realm are lost within all-consuming mists where there is no existence or time, due to an ancient catastrophe. Gameplay is about restoring lost realms into the fabric of reality and exploring/exploiting/helping/ruling/whatever those realms.
  • The setting defines seven elements that every thing and every action is composed of and aligned with, and can use these in a card-draw random generator to determine everything from a realm's inhabitants' government style to the fantastic geography to the realm's possible technologies.
  • The player characters are rebuilding the world in their own image as they rediscover lost realms and influence how they re-integrate with reality.

The world-generation system, then, relies on the fact that authority is shared and on the nature of the setting to harness the group's creativity to build out from the starting realm. The shared authority means that small contributions build up in unexpected ways into interesting, engaging places and events that nobody needed to construct (or even could have predicted) beforehand. The nature of the setting means that there is lots of room to build anything the players can imagine (really, anything is compatible, the way the world is defined in the book) and individual players can lean on their creative strengths.

The setting also means that there are natural bounds to play, so the mode of play switches to a creative building mode only when one of those limits is deliberately crossed by the group in order to discover what's over there. It handles during-play world creation as well as between-play solo creation, depending on how ownership is apportioned for the to-be-discovered piece of the world. The conceit that the PCs are shaping the rebuilt world in their own image makes the creative play mode parallel what is happening within the game: the player creating a realm represents their PC rediscovering a lost realm and influencing it's unfolding back into reality with their own personality.

The default way of playing is very non-traditional, but it also supports a more traditional GM/players division of labour simply by giving one player ownership of more kinds of things in the world – if all new realms are owned by the "world player", then one player can craft the world to their vision while the "character players" manipulate and explore it. It also spends a few paragraphs on using the system for different genres.

It's not a generic on-the-fly world-building system by far, but it's an interesting game technology and the only one that I know of that actually works seamlessly during play to give both structured results while being flexible and who and how it's used.



Microscope is a good example of what you're wanting, but it does not occur during gameplay of another game.

Essentially, it is a collaborative world-building game where you and the other players work together to create a universe. Play begins with a list of must and must-nots that the players determine one at a time, until someone declines to add something to the list. Following that, you pick the beginning time period, and ending time period, between which all of your events will occur.

Play begins with one player being the "lens" and determining the topic for this round of play - "the focus". Everything created this round should be related to that focus. An example might be "The Alderian Empire". Then each player takes a turn, and may create a Period, Event, or Scene relating to the topic. So on my turn, I might make the event "The destruction of Al'dui'nok, the Alderian Capitol", placing it within an appropriate era. The next player may then make a scene describing the fall.

The most interesting parts occur within scenes. These are designed to answer a question, and then the players act out how the scene plays out until the question is answered. For example, the player to my left might make "How did Ral'thia, queen of Alderia, escape from Al'dui'nok?". We would then pick parts (one player being Ral'thia perhaps, and other players perhaps playing the king, or guards, etc.), and then act out Ral'thia's escape from the city. I won't get into details on the rules surrounding scenes, but they are a good RP way to flesh out periods of history.

Perhaps this would fit the bill for you, and you might have a Microscope going in the background, and whenever a bit of history is revealed, you could play out a scene in Microscope to flesh out the piece of history or relevant geography you just discovered?


Burning Wheel.

While the rule system for burning the world as you go is fairly engrained in to the system, it's actually a pretty simplistic system:

  • At the outset of the campaign, you and your players answer questions to get "the wheel burning". It basically boils down to: What is your worlds theme? What guides it? What makes your world ripe for adventure? Is there magic? Faith magic? Other supernatural stuff? What is the local terrain? What are a few personality traits of your local people? Define a couple "big landmarks" in your world in a very fuzzy way. There was a spreadsheet hanging out on the Burning Wheel wiki at one point, but I'm coming up short. I doubt they want me reposting my copy somewhere just for the link. I know it's in the Adventure Burner these days, too.
  • As the story is told, the storyteller can create whatever details are necessary for the players to go through challenges. Generally the storyteller should work in the framework agreed upon by all the players, though.
  • While the story is in progress, players have "-wise" stats that can be used to create parts of the story. For instance, "City-wise" would allow the characters to roll and make up part of the city if they succeeded, or if they failed on their check, the storyteller gets to make up the detail instead! Here is a sample of the -wise stats: Sorcery-wise, city-wise, mountain-wise, weapon-wise, history-wise, et al. These stats are more or less "pulled out of nowhere". Some are prescribed, but they can be made up in the system, as needed.

Take a look at Dawn of Worlds. It's a simple game that collaboratively creates the world with the players acting as Hellenistic gods (of a sort). It's not "on the fly," "as you go," or sandbox-equse. More a game itself.

Most tools in this space will be front loaded with design by the GM, the players and GM, or as a game itself. I've used Dawn of Worlds before in all the aforementioned manners. However, reviewing the rules though I could see how you might be able to "go to god-mode" periodically to create "on the go."

However, using the Dawn of Worlds "ages" mechanic (a game round), I think the GM/GM+Players, would need to complete the first and second ages to establish the world. One would have to assume that certain races and beasts would have to be created--a doctrine of predestination of sorts--based on your game, e.g., if D&D, then elves, dwarves, halflings, etc. might be assumed available, but the peaks and valleys of rise, trade, war, fall, etc. might be created in game play of DoW and detailed in RPG play "on-the-go."


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