The "3D Model" is a model of role-playing styles, which maps out role-playing styles on two axes. Thus, the name is something of a misnomer, but arose out of the relation to the Threefold Model and GNS Model. The original idea for it was suggested by Mike Holmes in an August 2004 post to The Forge. (Holmes) However, there were many contributors documented in three Forge threads, and Vincent Baker suggested a similar model on his blog anyway. The 3D model was originally conceived of as adding a new dimension to the GNS model for player control over the game. The name is a misnomer since it only has two dimensions, but rather it associates "threefold" and adding an extra dimention.
There are two qualities which are mapped out in this model.
----Theme-----Immersion---Challenge-- _____________________________________ Centralized | | | | |___________|___________|___________| Guided | | | | |___________|___________|___________| Decentralized | | | | |___________|___________|___________|The nine individual categories are described in more detail below.
Focus is perhaps a vague variable, but it is visible by player attention. i.e. What elements are players concentrating on and paying attention to? What parts of the game do they talk about afterwards? These two might not be the same, but we are conflating them for purposes of this model. Centrality is trickier. Note that centralized play isn't necessarily railroaded. It may be collaborative by jointly creating the plan or cooperating under direction. However, it does not involve spontaneous reactions during active play. In other words, there is only one source which can majorly change the course of play: this could be a text source, the GM, or a vote of all the players.
Further details and examples:
The list of Challenge, Theme, and Immersion is not necessarily definitive. The category of Focus determines what part of the imaginative process is being paid attention to. There are a number of cases which are not completely clear, such as focus on comedy or genre emulation. These could conceivably be categorized in with either Theme or Immersion. For example, would a player-directed comedy game fit more with Theme/Decentralized -- which puts it in the same bucket as Primetime Adventures? However, perhaps since it is unclear, it would be better to define a different focus for entertaining story emulation. This would be focus on having a fun plot even if it doesn't have a consistent moral theme.
Another suggested focus was "Internal Causality". I would tend to say that internal causality is a technique, not a focus. Attention to the imaginative elements themselves is Immersion, but this may or may not use internal causality. Immersion is the sense of conveying the feel of person, places, or things. This can also be thought of as representation, or the vividness of portrayal.
The 3D Model was originally proposed in The Forge forum on the GNS Model, and the two models cover roughly the same ground. The distinction is that the 3D Model separates out the centrality of authorship. Within the 3D Model, Immersion/Centralized has generally been considered GNS Simulationism. Theme/Centralized has also been considered GNS Simulationism. Theme/Decentralized has generally been labelled GNS Narrativism. Expanding Mike's earlier diagram, this can be shown as:
----Theme-----Immersion---Challenge-- _____________________________________ Decentralized | | ??? | | | GNS Nar |___________| GNS Gam | Guided | | | | |___________| GNS Sim |___________| Centralized | | ??? | |_______________________|___________|
Note that I marked Immersion/Decentralized and Challenge/Centralized with question marks. I think that these regularly get classified differently under GNS by different people, or more often simply ignored as possibilities. The term "Open Sim" has been used on the Forge to describe some decentralized immersive games, such as my Water-Uphill World campaign. However, analysis of such campaigns went back and forth regularly between GNS categories.
Moreover, I feel that the 3D Model more successfully addresses the relationship between games. Though to some degree, this is inevitable simply in that it has nine categories instead of three, so it will show more. Notably, with the 3D Model, we can show a relationship between a group which is playing for "Theme" as a common feature -- but distinguishes between Theme/Centralized and Theme/Decentralized. I believe these are quite distinct, but their relation should be recognized.
Another relation of the GNS Model was proposed by Ralph Mazza (aka Valamir). In " The Model as seen by Valamir," he suggested that the sort of passive play, known as Illusionism or Participationism, is really a separate category of Creative-Agenda-less play. (Mazza 2004) In terms of the 3D Model, this would be a separate category. His forumation would map to the 3D Model, then, as follows:
----Theme-----Immersion---Challenge-- _____________________________________ Decentralized | | | | | GNS Nar | GNS Sim | GNS Gam | Guided | | | | |___________|___________|___________| Centralized | Creative Agenda-less Play | |___________________________________|
The 3D Model presents a related but distinct view of the concepts expressed by the Threefold Model and the GNS Model. It benefits from having more finely-grained categories -- nine instead of three. It also organizes them on two clearly-defined axes. While it does not necessarily replace the earlier models, it provides an alternative view. In principle, the separated axes may make this easier to apply to games in practice.
A potential difficulty for diagnosis is the idea that one's agenda in the game might be unconscious. One controversial aspect of GNS has been such unconcious distinctions -- i.e. for example, one consciously identifies one's play as GNS Narrativist, when really it is GNS Simulationist. This idea could apply as well to Focus in the 3D Model. For example, a group of players might consciously agree to focus on the Theme, but they end up each trying to outdo the other and the result is ultimately a focus on Challenge. However, it is generally more useful to trust players to make their own diagnoses.