The following diagram shows the alignment between the four Keirsey temperaments and the four Bartle Types:
Unified Model, Keirsey-Bartle Diagram
Here are some brief descriptions of each combination, showing how Keirsey and Bartle ascribe the same basic motivations to each temperament/type.
Idealist/Socializer: Socializers are described by Bartle as "... interested in people, and what they have to say. ... Inter-player relationships are important ... seeing [people] grow as individuals, maturing over time. ... The only ultimately fulfilling thing is ... getting to know people, to understand them, and to form beautiful, lasting relationships."
This is closely related to the Keirseian description of Idealists, who are very aware of other people as part of their lifelong journey of self-discovery (Internal Change). In a way, the highly imaginative Idealists are always roleplaying; they are constantly creating images of themselves (or others) that they feel they should model through their own actions in order to produce the emotions in themselves that they want to feel.
Guardian/Achiever: For the Guardian, the world is an insecure place, so it's necessary to protect oneself by accumulating material possessions... just in case. Thus, Guardians focus on earning money, on competing with others for resources perceived as scarce, on buying nice things and maintaining them, on forming stable and hierarchical group relationships, and generally on working hard to make their place in the world secure by locking down their connections to the world as possessions (External Structure).
Compare that to Bartle's description of Achievers: "Achievers regard points-gathering and rising in levels as their main goal" and "Achievers are proud of their formal status in the game's built-in level hierarchy, and of how short a time they took to reach it." Leveling up, leaderboards, and the accumulation of vast quantities of looted items are all behaviors that are driven more by a security-seeking motivation than by other motivations such as powerful sensations, understanding or self-growth.
This explains why the Guardian/Achiever is willing to persist in long stretches of "grind" that other kinds of gamers don't perceive as fun at all. To this gamer, rewards should be proportional to the amount of effort invested. When a game is designed around simple, well-defined tasks that enable the competitive accumulation of status tokens, that game is virtually guaranteed to attract security-seeking Guardian/Achievers.
Rational/Explorer: Rationals play in the same way that they do everything else -- they find pleasure in discovering the organized structural patterns behind raw data (Internal Structure). These can be patterns in space (as in geography) or patterns in time (as in morphology). Or they can be cause-and-effect patterns (entailment) or relationship patterns (connections). Ultimately, it's all about achieving a strategic understanding of the system as a whole thing.
As Bartle describes Explorers: "The real fun comes only from discovery, and making the most complete set of maps in existence." Of the core motivations -- sensation-seeking, security-seeking, knowledge-seeking, and identity-seeking -- exploration as "discovery" is most closely aligned with the Rational's knowledge-seeking preference. For the Rational/Explorer, once the principle behind the data is revealed, that's enough -- understanding is its own reward. These gamers can enjoy imparting knowledge to others, but no extrinsic reward for doing so is needed or expected.
Artisan/Killer: Finally, there are the Killers (or, as I prefer to call them, Manipulators). These can be difficult to understand in a gameplay context because most virtual worlds have encoded rules that marginalize their play style as "griefing" (i.e., upsetting other players) and try to prevent it. As Bartle puts it, "Killers get their kicks from imposing themselves on others." He also points out that Killers "wish only to demonstrate their superiority over fellow humans."
This desire for power over everything in their world is most closely echoed in the Keirseian description of Artisans, who (as their temperament name suggests) delight in the skillfully artistic manipulation of their environment. The Artisan/Killers are the tool-users, the adrenaline junkies, the natural politicians, the combat pilots, the high-stakes gamblers, and the negotiators par excellence. They instinctively find and exploit advantages in any tactical situation, and they express this need for dominance of their world in order to retain the greatest amount of personal freedom possible (External Change).
I believe a very good example of this can be found in Ryan Creighton's "social engineering" of the coin-collecting game at the Social Game Developers Rant of the 2011 Game Developers Conference. A Guardian/Achiever would have played by the rules and raced around the room begging others for their coins to try to win the game; an Idealist/Socializer would have asked for coins as a way to meet new people or help others win; and a Rational/Explorer would have sat quietly watching the flow of coin exchanges to try to understand the nature of the game. But an Artisan/Killer would instantly see how to short-circuit the designed system, and, as a born negotiator, would find it easy to persuade the person holding one of the bags of coins to hand the whole thing over... which is exactly what happened.
If the attendees needed to hear a rant from anyone, it would be the Manipulator who is out there, just waiting to exploit any opportunity to bring a little chaos to the carefully designed order of a social game. (See Ryan's description of the event for a wonderful first-hand account of gameplay from what appears to me to be a classic Artisan/Killer perspective.)
A final note on the Keirsey/Bartle linkage: the Keirsey temperaments and Bartle Types may appear not to line up directly where attitudes toward other people are concerned. This is because the Bartle Types were developed within a multi-player environment, which selects for more extroverted, sociable gamers, while the temperaments include both extroverts and introverts.
So, for example, the "Socializer" term that makes sense within the Bartle Types for its emphasis on interacting with other people can seem not to apply to an introverted Idealist who prefers to play single-player games. These less-social Socializers are more likely to prefer individualized entertainment or abstract games, making it difficult to distinguish them from Rational/Explorer gamers. Closer study is usually required to see whether their primary reason for playing is to feel good (an Idealist preference) or to exercise their thinking skills (a Rational goal).
Even taking introversion and extroversion into account, not everyone fits neatly into one of the four fundamental temperaments. This aspect of reality isn't well described by the four-fold Bartle or Keirsey typologies. Some people feel equally drawn to Internals and Externals, or to Change and Structure.
The book 21st-Century Game Design, edited by Christopher Bateman, explores a "demographic game design" model (DGD1) of gameplay preferences that I believe forms a useful counterpoint to the Keirsey/Bartle model of general personality. Rather than matching each of the types and temperaments, the Bateman play styles appear to be secondary styles that fill in the gaps between the primary play styles.
All of the elements that Bateman defined for his four play styles as well as for the Hardcore and Casual modes appear to map not directly onto the Keirsey/Bartle map, but into each of the gaps between the four Keirsey/Bartle styles. The following diagram shows this overlaid relationship:
Unified Model, Keirsey-Bartle Diagram with Bateman DGD1 Model Overlaid
The value of the DGD1 model (beyond the utility it has in and of itself as a model of personality) is that it provides a direct response to one of the most common criticisms of the Bartle Types model, which is that "no one is ever just one 'type' of player." The DGD1 model fills in the gaps between the Bartle Types. A gamer who knows that his preferred style of play is balanced between exploration and achievement, or a combination of Strategic (Rational) and Logistic (Guardian) play, who was told he "didn't fit" the Bartle model, can now understand himself to be representative of the Conqueror play style as described by the interstitial DGD1 model. Rather than invalidating the Bartle Types, the DGD1 model deepens and refines that model of play styles, leading to the merged Keirsey/Bartle/Bateman model whose structure is shown in the diagram above.
Note: Following the publication of 21st-Century Game Design, a questionnaire for a DGD2 model was developed and added to the iHobo site. Drawing from lessons learned with the Myers-Briggs-based DGG1 model, the DGD2 model was built more explicitly around the four temperaments described by Keirsey. Rather than breaking or changing the play style model developed for DGD1, the application of concepts from Keirsey's temperament theory appeared to sharpen the DGD-based Conqueror, Manager, Wanderer and Participant styles as complementary to the four Keirsey temperaments (and thus the four Bartle Types as well). (A subsequent model, BrainHex, follows a six-pattern typology.)
As I explored the literature on player styles and models of gameplay, I was surprised to see how many of these other models proposed three or four categories. Even more remarkably, in many cases the descriptions given by the various authors for each of their categories sounded very much like the descriptions of the core play styles in the Keirsey/Bartle model.
As a result, the second major assertion I'm making in this article is that not only are the four Bartle Types a play-context subset of the four general Keirsey Temperaments, there are numerous other well-known models of play and game design that are also variations on the exact same set of four fundamental personality styles.
It's important to acknowledge that there are other models of personality and play that do not appear to be variations on the same four essential styles. I understand that; I have no interest in trying to stuff every personality model I see into this one. As an experienced designer of systems, I'm very aware of the danger of seeing every phenomenon as a confirming instance of one's pet theory. I've done my best to avoid that error by identifying as a facet of the Unified Model only those systems for which multiple elements appear to align closely with the other systems in the model.
This chart presents the basic concepts of each play style or personality model using words their creators selected as being generally representative of each worldview. It's intended to be an at-a-glance representation of the associations between styles of play and layered models of game design. It also references three general models of personality in functional group situations (usually the office or workplace), as well as three ways in which I've tried to boil down the four perspectives to their essential meanings.