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Return to the GMIS

Posted by mr_orgue on 2008.04.01 at 12:48
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As I was walking to university today, my brain was turning on the GMIS stuff that I raised with enthusiasm last year, before it all got bulldozed by being incredibly busy all the time. (Short version: in traditional games, the GM has a model of the gameworld going on in his head that includes stuff players don’t know about, like the assassin hiding in the closet or the fact that the book the players have been carrying around has a treasure map concealed inside. Looking closely at how the GM manages that model should give us some insights.) (Long version: the SIS tag tracks all of these entries. Go read.)

So, some notes about where my head is at on this stuff today:
  • RPGs consist of narratives that take place in imagined worlds.

  • The core activity in RPGs is player-character interaction with an imagined world.

  • The imagined world is functionally represented as each participant’s imagined space (player imagined space, PIS, and GM imagined space, GMIS).

  • The GMIS is privileged over the PIS, because the GM is entitled and indeed required to imagine the world from a godlike perspective instead of a character perspective.

  • The GMIS is a mental model held and maintained by the GM.

  • The GMIS can therefore be approached as a cognitive problem.

Because it is instantiated primarily in the GMIS, the imagined world is limited by the scope of the GM’s mental model and governed by the GMs set of techniques for manipulating their mental model.

There is a useful distinction between the active GMIS and the extended GMIS.
  • The active GMIS is the mental model active in the GM’s mind at any given moment. It exists in the GM’s short-term or working memory.

  • The extended GMIS is information that stretches outside of the active GMIS, including material in long-term memory, material in game notes, material in setting sourcebooks, etc.

The active GMIS at any time can be modelled as a list of entities, which are concrete things in the imagined world. Each of these entities is tagged with a list of aspects, usually a short list. (See example below.)
  • The most important aspect is purpose. From the purpose aspect, the GM can derive moment to moment actions for the entity. Some entities will not have a purpose because they are inanimate objects; player characters don’t have purpose aspects in the GMIS because the GM is not required to derive their actions.

  • The second most important aspect is actually a set of aspects: the relationships between the entity and all other entities in the GMIS. This includes matters such as position and awareness. From these aspects, the GM can derive moment-to-moment reactions for the entity.

There must be some way of managing the order and timing of actions by entities. Initiative systems take care of this in some conflict scenes for some games, but outside of this it is usually managed in an ad-hoc way by the GM.

Each time an entity acts, the GM must run through each other entity in active GMIS and, with reference to their relationship to that entity, update their aspects to reflect the action taken. (If this is in a strict initiative-based situation, this task can be handled in initiative order as each entity comes up.)

The fundamental communication task of the GM in a traditional game is to ensure players know all of the entities in the scene (or the subset of those entities of which the player-characters are aware), and the obvious relationships between them. Other qualities of the scene are not fundamentally important – the game will still function without this communication.

The Shared Imagined Space (SIS) does, then, exist – it is the set of entities and aspects that have been successfully communicated from the GM to all players and are therefore identical in the GMIS and in each PIS.

The SIS is *not* equivalent to the imagined world. The SIS is a specific subset of information about the imagined world. Each participant, in fact, develops their imagined world based on the content of the SIS. Each participant’s imagined world is necessarily unique.

The active GMIS can include no more than seven entities, including the player character group, without breaking down in some way, due to limits in human working memory capacity. This limit can be extended by techniques such as chunking (treating groups of characters as one entity), and using external resources (such as miniatures on a battlemat).

Example instance
Context (not an entity): a subset of the player-character group are confronting a suspected kidnapper in a seedy bar.

Entities in the active GMIS are listed below with their aspects. Those that exist in player awareness are marked with an asterisk. It is the GM’s responsibility to communicate all asterisked entities and aspects to players; these items constitute the SIS.

Entity: Big John Boots, kidnapper *

  • wants to pass himself off as innocent

  • sitting at a central table *

  • not intimidated by the PC group *

  • has a concealed weapon

  • game statistics are located in my notes

Entity: PC group *

  • surrounding Boots *

  • just tried, unsuccessfully, to intimidate him *

Entity: Squad of hired killers

  • On their way to kill Boots

  • Not yet close enough to be heard

Entity: Sly Richard, informant

  • In it for the cash reward

  • Waiting for the squad of killers

  • Lurking in a corner watching Boots, and now the PCs

Entity: Seedy Bar *

  • no particular purpose

  • has a bartender and other customers *

  • contains Boots and the PC group *

  • contains Sly Richard

Say the PCs decide to pull weapons on Boots. The GM will run through the other entities, and decide that the Seedy Bar entity will react. He could say “the bar falls silent and people start hiding”, or promote the bartender into an active entity, “the bartender comes over to the table and tells you in no uncertain terms to put the weapons down and clear out”. The GM might also decide that Sly Richard follows his self-preservation instinct and gets out of there, removing Sly Richard from the scene as an active entity.


mashugenah at 2008-04-21 19:59 (UTC) (Link)
Interesting thread of stuff here Morgue, but I can't help but get the impression this is the projection of a larger bulk of information rather than a complete picture. (You know I've read your other GMIS stuff. This carries on from that, but immediately starts suggesting solutions without problem-solving forms or working. i.e. "There is a useful distinction between the active GMIS and the extended GMIS."

Useful in what way? How is this implemented? What would I be doing instead?

The two bullets which follow seem useful, but I can't understand why you're dividing up the GMIS in this way.)

So... and interesting fragment. How does this work towards completing the picture you've been painting in your GMIS work so far?
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