Richard Bartle co-created MUD (Multi-User Dungeon), the text-based precursor to today’s MMORPGs, while studying at Essex University. He ended up formulating the theory that all MUD players could be broken down into four main types: killers, achievers, explorers, and socializers. This theory has since been used in all sorts of game design situations.
Bartle theorized that MUD players could be split into four types, giving psychological portraits of players populating a virtual world for fun:
- Killers like to provoke and cause drama and/or impose them over other players in the scope provided by the virtual world. Trolls, hackers, cheaters, and attention farmers belong in this category, along with the most ferocious and skillful PvP opponents.
- Achievers are competitive and enjoy beating difficult challenges whether they are set by the game or by themselves. The more challenging the goal, the most rewarded they tend to feel.
- Explorers like to explore the world – not just its geography but also the finer details of the game mechanics. These players may end up knowing how the game works and behave better than the game creators themselves. They know all the mechanics, short-cuts, tricks, and glitches that there are to know in the game and thrive on discovering more.
- Socializers are often more interested in having relations with the other players than playing the game itself. They help to spread knowledge and a human feel, and are often involved in the community aspect of the game (by means of managing guild or role-playing, for instance).
The horizontal axis represents a preference for interacting with other players vs. interacting with the world and the vertical axis represents a preference for (inter)acting with something vs. (inter)acting on something. So, achievers prefer to act on the world, while socializers prefer to interact with other players.
Bartle found that players tended to belong to a primary category, but drifted between several others depending on their mood, situation and preferred goal in the game. Having categorized those type of players, drawn to the same virtual world for different reasons and still acting and interacting in the same playing field, he was now able to better balance the game.