Kinds of Player Skill

Diegetic Thinking Skill

The term "diegetic" comes up most often in terms of sound in movies. A nondiegetic song is one the audience can hear (like a theme song over the credits) but the characters can't. Diegetic, conversely, refers to songs or dialogue that the characters are supposed to be hearing, too, like if somebody turns on a radio.

Diegetic Thinking Skill is basically when a player is good at imagining themselves as having the same constraints and opportunities their character would have in the game world. Like "Wait, you said every house here had a fireplace, right? That means there must be a chimney, and if there's a chimney then we can..."

Decent Diegetic Thinking requires that the GM and player be basically on the same page as far as what kind of logic and physics apply in the gameworld, or at least in the part of the gameworld they are talking about at the time. This gets harder the more fantastic the gameworld is.

Like: is a medusa vulnerable to the same kind of venom produced by the snakes coming out of her own head? There is normally no diegetic way for a player to figure that out (outside in-game testing or asking an in-game authority) since it is essentially wholly in the hands of the GM's ideas about gameworld biology.

In practice, the best way to encourage and enable diegetic thinking is for the GM to constantly communicate to the players what the current "grit level" of the fiction is. Like "This is pretty much a typical village" or "You are Baba Yaga's house, everything is enchanted and strange..." and sometimes this will require the GM communicating Extradiegetically (that is--talking directly to the players rather than acting as their characters senses), like: "If it'd catch on fire in real life, it'll catch on fire here" or "This is some kinda mystic flame and you don't know what it'll do and there's no way to find out without just trying stuff". This requires good GMing--possibly a level of good GMing you can't expect from an inexperienced GM.

An alternative way to describe "grit level" is trying to get everybody thinking in terms of the same kind of fiction--like "we use Star Trek logic here" or "we use John Woo logic here". This is really hard when the PC actions involve any element of the fantastic--Can we modify the deflector array to do that? Who the fuck knows? However (as in the illustration at the top of this blog entry here) very often the PC's actions themselves involve no fantastic actions despite the fact that they exist in a fantastic world.

From the GMs point of view: if your players consistently find diegetic solutions to problems in terms that you didn't expect but that fit easily within the ideas you already had of what's possible according to the physics and metaphysics in the gameworld (like you think "oh yeah, you could do that, I can't think of any reason why not..."), then you're probably doing a pretty good job of communicating the grit level of the game.

If you argue a lot about it, you're probably not.

If you hear a PCs plan and go "Hmmm...well it could work like that I guess..." then you change or expand your idea of how the gameworld works to accomodate the players you are basically working with the PCs to "create" a solution by changing or expannding the game logic so it works like that and they are kind of getting Extradiegetic about it.

The most important idea here is: once an idea about how stuff works is communicated, it becomes true. Like in common law.

An example of an edge-case was when I tried to saturate a donkey with holy water to act as a baited trap for vampires. It had already been established in-game that vampires would suck the blood out of donkeys (definitely diegetic logic), but the idea that holy water would stay holy once a donkey drank it and would stay in the animal's bloodstream long enough to matter once the vampires drank it was probably all stuff the GM--Jeff--hadn't considered and just went with because it seemed like a fun plan (extradiegetic).

You could argue that if Jeff checked both Christian catechisms and biology textbooks before telling me if my plan was plausible then we've got a wholly diegetic plan, but then I'd counter that I had no way of knowing which authorities were considered true in the gameworld (as obviously the existence of vampires at all implies at least a certain level of folk-science is in play).

Diegetic solutions do not usually require system mastery. They require understanding the fiction--often merely a small part of it.

Extradiegetic Thinking Skill

This is player skill at thinking about or manipulating something that exists as part of the game but not part of the fiction.

A good example is in the (totally sweet) game Dread where your character's fate depends on ability to pull Jenga blocks from a Jenga tower. Another example would be a mechanic which allows you to choose to roll 1d10 or 2d6-pick-the-highest without any corresponding in-game explanation for what these two different die set-ups represent. Another example would be the oft-cited "If it just sounds cool, then the GM will let you try it" policy.

Often Extradiegtic Thinking requires some element of system mastery, but not always. In the above examples, the one with the dice requires system mastery, the Dread one kinda does (if you consider pulling blocks the "system".) The third one involves "mastering" or simply "impressing" the GM.

A large part of player skill is about weighing odds based on character skills--if a character can attempt to do something using two separate skills, like "Library Use 20% " or "Journalism 30%" and opts for Journalism because they have a better chance then it's diegetic skill unless the character for some reason doesn't know they suck even worse at using libraries than being a reporter, then it's extradiegetic.

Sir Arthur Conan Doyle has Extradiegetic thinking Skills (required to write the story, not just the solution to the murder) and Diegetic Thinking Skill. The reader who solves the mystery while reading before Holmes does using only information provided in the story and science as it was understood up until Holmes' time has Diegetic Thinking skill. The reader who solves the mystery using literary savvy about what kinds of solutions Doyle was likely to come up with given his literary sentiment has Extradiegetic Skill.

Creativity

This is, quite simply, the ability to make stuff up that is interesting. Like, say, an interesting character background. It's purely subjective, until it becomes....

Creative Problem Solving

This is the ability to make stuff up that is interesting and original (the subjective part) and which also accomplishes a specified game goal (the objective part). Like: "Your character has two magnets and three daggers, make a trap out of that" or "Give me a character background that explains why you have a nose like a turnip and three peanuts in your pocket."

CPS can be diegetic (the first example--the trap--could be) or extradiegetic (the second example--the turnip story).

Mimetic Skill

Basically: Player is good at doing something therefore the character is good at a similar thing, too. There is almost always a "translation gap" involved in mimetic skills and so it's hard to say exactly how "true" the equivalence is.

Example: A Rolemaster player or 4e player in charge of Aragorn is good at telling other players what fighting techniques to use for generally optimum effectiveness on the battlefield just the same way Aragorn is a great tactician.

Or: A player is quick-witted and funny in acted dialogue and makes the other players laugh and so the NPCs also laugh.

Or: deciding someone's PC can't spell because the player misspelled "captain" in that note up there.

This kind of thing overlaps with Extradiegetic Skill if these tactics require weighing of numbers or factors that would matter in the kind of game being played but not if the situation were actually occurring (again, any element of the fantastic can make this hard to judge). That is: a great general might be good at Risk even though many of Risk's tactical rules are extradiegetic because it (perhaps) requires the same kind of brain, just using it to think in different terms.

This usually overlaps with Diegetic Thinking in one way or another, though it is possible to set up situations where it doesn't require actual thinking, like: player throws a dart at a target to determine whether a character manages to hit a target or (and I've done this one) hand the player a maze to solve and as soon as they finish their PC has escaped a maze. In this case the GM has essentially decided that the players' real life skill should be mapped to a character skill and the player hasn't really had to think in-world at all.

The Jenga-block mechanic in Dread is definitely not Mimetic but could suddenly be if the GM created a scenario where the characters were facing an Indiana-Jonesish puzzle where they were pulling blocks out of an ancient idol to get to a treasure without triggering a curse.

___
The edge cases here are legendary--these occur, for example, every time you see two people arguing over whether a flanking formation should give them a +1 or +2 bonus and whether this is "realistic" and on and on forever.

However, for practical purposes we can say:

-That it is really hard to tell which tactical game mechanics represent actual pieces of mimetic logic and which represent strictly extradiegetic logic made up to make the game work.

-Actual practical military wargames used for actual training of actual military people from Napoleon's time to our own are based on the idea that modelling at least some mimetic situations is possible.

-Whether the mimesis is "true" or not, being good at these kinds of things is a skill.

___

Notes: there are some clarifications on some of this stuff below in the comments.