A marble is 1 piece of a set that makes a coherent unity. The set might be a set of scenes that together forms a story or it can be a set of clues to uncover the truth of a mystery, conspiracy, a web of lies or other the pre-written truths designed by the organisers.
The idea is that a participant at a larp will encounter clues or incentives in much the same way as someone pulling random marbles out of a bag.
The metaphor of the bag of marbles is used in figuring out probability in math. (The math behind it is described as the "Bags of Marble" puzzle and can be searched on the internet using "math theory" & "bag of marbles").
The essence of a marble structure is to regard a game-location including the characters present as placeholders for clues. Like a marble in a closed bag of marbles are the clues hidden from view. Every encounter either with the environment is regarded as a possible situation that would give the player access to another clue. This could be a character(not player), objects, piece of scenography or even a view of the landscape that gives the player a clue on how to solve a prewritten puzzle or mystery. The trick is that a player would need a minimum number of clues before being able to realize the hidden truth. Also usually there are at any given game parallell storylines. As the metaphor the bag of marbles have several colors of marbles. How many do you have to draw to have 5 of the same color? This is a classic mathematic problem related to organic structures. (a topic Erlend Eidsem Hansen studied during his early years in object oriented computer programming.)
This is contrary to reading a book (which is a chronological action, page after page, scene after scene, like a railroad has stations along the line). It is also contrary to playing most computer games (which usually has a branching structure in the storyline, that you get alternate ways but the interactivity is deciding alternate actions and getting alternate endings. It is not a free choice, it is a limited list of choices in one scene. The Swedish Interactingarts Collective would name this in their book "Deltagerkultur" as Interactivity, but not as Interaction).
Scene structure - the modern interpretation Bag-of-marbles - Chosing any available scene – collecting enough scenes to form a story - also possibly repeating scenes already done in a new way This relates strongly to what mathematics refer to as Pigeonhole principle.(http://en.m.wikipedia.org/wiki/Pigeonhole_principle) - Apparently also it relates to 'database narrative' - this link might give you some more meat on the bone: http://tigerlilynewmediatheory.blogspot.no/2005/11/kinder-in-western-academic-theory.html?m=1
An example is this: Presume that in a box there are 10 black socks and 12 blue socks and you need to get one pair of socks of the same colour. Supposing you can take socks out of the box only once and only without looking, how many socks do you have to pull out together? When asked point-blank, people may sometimes unthinkingly give answers such as "thirteen", before realizing that the correct answer is obviously "three". To have at least one pair of the same colour (m = 2 holes, one per colour), using one pigeonhole per colour, you need only three socks (n = 3 objects). Think of the socks as elements of a plot-sequence or as scenes or plot-objectives needed to be achieved.
(compared to fates that explains everything:) There are several different interpretations of the fateplay idea, but they usually involve an instruction that the player should be able to achieve easily, with the challenge being more about achieving it in an interesting an meaningful way. For example a character might be given the fate that "Before the second night of the larp, you shall challenge the king to a duel on the third morning. You will lose this duel." The duel is unavoidable, but the details of the challenge and the fighting leave plenty of space for dramatic improvisation.
Fates may be inter-connected into a "fateweb" where individual fates reveal their meaning as they are carried out. For example, the King in the above example might be fated to reveal his complicty in the murder of the previous King before the second day, thereby providing a motivation for the character fated to challenge him to a duel.
Marbles may be used to adopt whole narratives to larp - e.g. stories derived from mythology, theatre plays and the like. "Light-weight fates" may be used to give the players good ideas for what to do during the larp. There are also examples of larps where the first part of the larp is fated, and the fates are used to establish interesting conflicts, while the rest of the larp is controlled by theory of marbles.
History and further reading
Theory of marbles was probably "invented" (or its relation to larpdesign discovered) in Norway. Erlend Eidsem Hansen published an article about larp dramaturgy dividing plotstructures into 3 main strategies : railroading, branching and marbles in his underground larpfanzine "Guru" in 1993. Also some (old) texts on larphacking are gathered at: Larp Hacking Wiki (the wiki is referring to a workshop at KP 2007 and a roundtable/panel-discussion in SK 2008).
Notable usages of this technique
- Nosferatu, 1994, 1995, 1996, 2013