TTRPG•ML

Sketch for a tabletop role-playing
game markup language

• By David Moles
• School of Communication and Information
• Rutgers, The State University of New Jersey
• 17:610:524:90 Metadata for the Information Professional
• Jessica Yi-Yun Cheng, Ph.D., Instructor
• Fall 2023

• Composed and published with mdBook.
• Text set in League Spartan, with code in Courier Prime and titles in Sorts Mill Goudy.
• Illustration generated by Adobe Firefly.

Background: Domain and Potential Users

Domain

I myself am a dilettante when it comes to tabletop role-playing games (RPGs), more of a collector than a player and more of an accumulator than a collector, but I find the theory of game design and the history of games and gaming interesting, and include among my friends many more serious hobbyists, including some successful independent game designers.

For my project, I propose to develop a metadata schema for describing tabletop RPG systems—that is, not games themselves, but families of games defined by shared rules, design decisions, and in some cases (e.g. Alder, n.d.¹) even theme and emotional tone. Some, such as the d20 System² published by Wizards of the Coast as a derivative of the long-running Dungeons & Dragons series, are rigidly defined, intended and licensed for commercial use; others, such as Vincent Baker’s Powered by the Apocalypse³, are more like philosophical approaches to game design open for adoption and adaptation, in whole or in part, by both amateur and professional designers.

Each system captures a set of design decisions and intentions that differentiate the systems from one another while creating commonalities among games based on the same system, and systems also are related to one another both historically and structurally; these characteristics seem amenable to capture and description in a controlled, structured way, perhaps drawing on work such as that of Zagal and Deterding on gameplay design patterns.⁴

Potential users

Potential users of the metadata schema include game designers, scholars of RPG studies (a growing field which now includes its own peer-reviewed journals, such as the International Journal of Role-Playing⁵ published by the Department of Game Design at Uppsala University), developers of websites or databases collecting RPG information, and serious bibliographers of RPGs (the last two categories likely having some overlap). Some of these audiences might find the process of taxonomizing systems and creating controlled vocabularies more valuable than the documents produced; the schema would nonetheless facilitate doing so in a structured way. Some of these audiences might find the schema useful for (meta)data collection and analysis; others as an interchange format, or as the basis for a display system; a URI-addressable reference database of RPG systems might also be a linked data resource for other collections of linked data on role-playing games and gaming.

Related Standards

Related schemas

I have chosen to include here only very general XML schemas that I either leveraged directly, or that inspired some elements of the design.

The Dublin Core Terms¹ schema is referenced directly for domain-agnostic metadata such as creator, date, rights, and so on. However, certain elements that might appear similar to elements from Dublin Core Terms, such as <identifier> and <rights>, are defined separately in order to allow for more structure than the simple string values of Dublin Core.

The use of an <alt-title> element to represent abbreviations, nicknames, and so on, and an associated attribute @alt-title-type to represent the semantics of the alternate title, is inspired by the <Title> element and @titleType attribute from DataCite 4², but I decided against incorporating the DataCite element and attribute directly in order to separate main and alternate titles, and to be able to incorporate additional (alternate) title types.

I also considered including MODS³ to represent bibliographic references for specific game publications, such as the game book in which a particular system was introduced, or later games based on the same system, but in the end decided to keep bibliographic information minimal, pro tem.

Other related work

I found no previous work on representing tabletop role-playing game systems or rulesets, and only a limited amount of work on representing the games themselves, or even related works such as boardgames; what I did find was generally not oriented toward XML, e.g. McCulloch⁴, on cataloging boardgames with MARC, or Franco et al.⁵, on representing semantics of either computer or tabletop role-playing games in UML. There is a considerable if scattershot literature on representing video games, including computer role playing games, and some on representing rules or game semantics, including again Franco et al., and also e.g. Zagal et al.⁶ on identifying game design elements and their relationships; but again, none of it is XML-based (most, in fact, seems to give very little consideration to interoperability or reuse at all).

That said, there is also a rich if informal literature among gameplayers and designers discussing game systems, rules, and mechanics, and essays like Edwards⁷ on the relevance of mechanics to gameplay or Mary Kuhner’s “threefold model”⁸ seem likely to provide fruitful avenues for developing taxonomy and vocabulary.

Data Dictionary

Note: The TTRPG•ML schema uses both original elements and embedded elements from Dublin Core Terms.

TTRPG•ML Elements

Dublin Core Terms Elements

Element definitions

rpg-systems

Note: The systems in the collection may bear some intellectual relationship to one another or be organized simply for convenience. Empty collections are allowed.

rpg-system

Note: These properties, with the exception of style, and games, can also be specified at the game level. Properties not specified for a game are presumed to be inherited from the parent rpg-system.

alt-title

edition

Note: Different editions of a game or system should be recorded as individual game or rpg-system elements.

identifier

scope

resp-stmt

Note: At least one of dct:creator, dct:contributor, or dct:publisher must be specified; however, any number can be specified, in any order.

rights

style

style-name

Note: For other play styles not captured by this controlled vocabulary, use style-note.

style-note

games

Note: Empty collections are allowed.

game

Note: This is the same set of properties as rpg-system, except that style and games are omitted. Properties not specified for a game are assumed to be inherited from the parent rpg-system.

copyright

rights-uri

note

dct:creator

dct:contributor

dct:publisher

dct:date

dct:title

dct:source

dct:description

Schema

Download schema file

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
  xmlns:dct="http://purl.org/dc/terms/"
  xmlns:html="http://www.w3.org/1999/xhtml"
  xmlns:xml="http://www.w3.org/XML/1998/namespace"
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xmlns:vc="http://www.w3.org/2007/XMLSchema-versioning"
  vc:minVersion="1.1"
  xmlns="https://dmoles.info/ttrpgml-0.1"
  elementFormDefault="qualified"
  targetNamespace="https://dmoles.info/ttrpgml-0.1"
>
  <xs:import namespace="http://purl.org/dc/terms/" schemaLocation="https://www.dublincore.org/schemas/xmls/qdc/2008/02/11/dcterms.xsd"/>
  <xs:import namespace="http://www.w3.org/1999/xhtml" schemaLocation="https://www.w3.org/2002/08/xhtml/xhtml1-strict.xsd"/>
  <xs:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="http://www.w3.org/2001/xml.xsd"/>

  <xs:element name="rpg-systems">
    <xs:annotation>
      <xs:documentation>
        Container type for a collection of RPG systems. The
        collection may bear some intellectual relationship to one
        another or be organized simply for convenience. Note that
        empty collections are allowed.
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="rpg-system"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name="rpg-system">
    <xs:annotation>
      <xs:documentation>
        A tabletop role-playing game system (as distinguished from
        particular games using the system).
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:complexContent>
        <xs:extension base="game-or-system">
          <xs:sequence>
            <xs:choice minOccurs="0" maxOccurs="unbounded">
              <xs:element ref="style"/>
            </xs:choice>
            <xs:element minOccurs="0" ref="games">
              <xs:annotation>
                <xs:documentation>
                  <html:strong>Note:</html:strong>
                  <html:code>game</html:code> properties not specified are assumed
                  to be inherited from the parent <html:code>rpg-system</html:code>.
                </xs:documentation>
              </xs:annotation>
            </xs:element>
          </xs:sequence>
        </xs:extension>
      </xs:complexContent>
    </xs:complexType>
  </xs:element>

  <xs:element name="alt-title">
    <xs:annotation>
      <xs:documentation>
        An alternative title for a game or game system, such as a nickname,
        abbreviation, subtitle, or translated title.
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="type" type="alt-title-type" use="required"/>
          <xs:attribute ref="xml:lang"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

  <xs:element name="edition">
    <xs:annotation>
      <xs:documentation>
        An edition of a game or system. Different editions of a game
        or system should be recorded as individual
        <html:code>game</html:code>
        or <html:code>rpg-system</html:code> elements.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="identifier">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="type" use="required"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

  <xs:element name="scope">
    <xs:annotation>
      <xs:documentation>
        The size and scope of a game, e.g. the required/suggested number of players,
        time per session, whether or not the game is intended for a multi-session
        campaign, etc.
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="players">
            <xs:annotation>
              <xs:documentation>
                The required or suggested number of players of a game. Often
                expressed as a range, e.g. <html:code>3-6</html:code>.
              </xs:documentation>
            </xs:annotation>
          </xs:attribute>
          <xs:attribute name="session-time">
            <xs:annotation>
              <xs:documentation>
                The required or suggested time for a game session. Often
                expressed as a range, e.g. <html:code>2-3 hours</html:code>.
              </xs:documentation>
            </xs:annotation>
          </xs:attribute>
          <xs:attribute name="campaign" type="xs:boolean">
            <xs:annotation>
              <xs:documentation>
                Whether or not the game is intended to be played as a multi-session
                campaign.
              </xs:documentation>
            </xs:annotation>
          </xs:attribute>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

  <xs:element name="resp-stmt">
    <xs:annotation>
      <xs:documentation>
        A statement of responsibility for a game or system.
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:choice maxOccurs="unbounded">
          <xs:element ref="dct:creator"/>
          <xs:element ref="dct:contributor"/>
          <xs:element ref="dct:publisher"/>
        </xs:choice>
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="dct:date"/>
        <xs:element minOccurs="0" ref="note"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name="rights">
    <xs:annotation>
      <xs:documentation>
        Rights information for a game or system.
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:choice minOccurs="0" maxOccurs="unbounded">
          <xs:element ref="copyright"/>
          <xs:element name="rights-uri" type="xs:anyURI"/>
        </xs:choice>
        <xs:element minOccurs="0" ref="note"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name="style">
    <xs:complexType>
      <xs:choice>
        <xs:element ref="style-note"/>
        <xs:sequence>
          <xs:element maxOccurs="unbounded" ref="style-name"/>
          <xs:element minOccurs="0" ref="style-note"/>
        </xs:sequence>
      </xs:choice>
    </xs:complexType>
  </xs:element>

  <xs:element name="style-name">
    <xs:annotation>
      <xs:documentation>
        A style of play associated with a game or system, e.g.
        gamist, narrativist, or simulationist.

        <html:strong>Note:</html:strong>
        For other play styles not
        captured by this controlled vocabulary, use
        <html:code>style-note</html:code>
      </xs:documentation>
    </xs:annotation>
    <xs:simpleType>
      <xs:restriction base="xs:string">
        <xs:enumeration value="gamist"/>
        <xs:enumeration value="narrativist"/>
        <xs:enumeration value="simulationist"/>
        <xs:enumeration value="freeform"/>
      </xs:restriction>
    </xs:simpleType>
  </xs:element>

  <xs:element name="style-note">
    <xs:annotation>
      <xs:documentation>
        An explanatory note regarding play style.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="games">
    <xs:annotation>
      <xs:documentation>
        A collection of games associated with a game system.
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="game"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name="game">
    <xs:annotation>
      <xs:documentation>
        A tabletop role-playing game.
        <html:strong>Note:</html:strong>
        properties not specified are assumed
        to be inherited from the parent <html:code>rpg-system</html:code>.
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:complexContent>
        <xs:extension base="game-or-system"/>
      </xs:complexContent>
    </xs:complexType>

  </xs:element>

  <xs:element name="copyright">
    <xs:annotation>
      <xs:documentation>
        Copyright information for a game or system.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="note">
    <xs:annotation>
      <xs:documentation>
        An explanatory note attached to other elements.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:complexType name="game-or-system">
    <xs:sequence>
      <xs:element ref="dct:title"/>
      <xs:element minOccurs="0" maxOccurs="unbounded" ref="alt-title"/>
      <xs:element minOccurs="0" ref="edition"/>
      <xs:element minOccurs="0" ref="identifier"/>
      <xs:element minOccurs="0" maxOccurs="unbounded" ref="dct:source"/>
      <xs:element minOccurs="0" ref="scope"/>
      <xs:element ref="dct:description"/>
      <xs:element minOccurs="0" ref="resp-stmt"/>
      <xs:element minOccurs="0" ref="rights"/>
    </xs:sequence>
  </xs:complexType>

  <xs:simpleType name="alt-title-type">
    <xs:annotation>
      <xs:documentation>
        Controlled values for the <html:code>alt-title</html:code> element's
        <html:code>title-type</html:code>
        attribute.

        Inspired by
        <html:a href="https://schema.datacite.org/meta/kernel-4.4/">DataCite 4</html:a>'s
        <html:code>titleType</html:code>.
      </xs:documentation>
    </xs:annotation>
    <xs:restriction base="xs:string">
      <xs:enumeration value="abbreviation"/>
      <xs:enumeration value="nickname"/>
      <xs:enumeration value="subtitle"/>
      <xs:enumeration value="translation"/>
      <xs:enumeration value="other"/>
    </xs:restriction>
  </xs:simpleType>

</xs:schema>

Sample Records

1. Alder, A. & Rosenbaum, B. (2021) Belonging Outside Belonging.
2. Tweet et al. (2000). The d20 System.

Alder, A. & Rosenbaum, B. (2021) Belonging Outside Belonging.

Download ttrpgml-0.1-example-1.xml

<?xml version="1.0" encoding="UTF-8" ?>
<rpg-system
  xmlns="https://dmoles.info/ttrpgml-0.1"
  xmlns:dct="http://purl.org/dc/terms/"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="https://dmoles.info/ttrpgml-0.1 https://dmoles.info/ttrpgml-0.1.xsd http://purl.org/dc/terms/ https://www.dublincore.org/schemas/xmls/qdc/2008/02/11/dcterms.xsd"
>
  <dct:title>Belonging Outside Belonging</dct:title>
  <alt-title type="abbreviation">BoB</alt-title>
  <identifier type="wikidata">Q109853477</identifier>
  <dct:source>https://buriedwithoutceremony.com/belonging</dct:source>
  <dct:description>
    A narrativist, "no dice, no masters" system about marginalized groups establishing
    community in resistance to or evasion of a dominant culture.
  </dct:description>
  <resp-stmt>
    <dct:creator>Avery Alder</dct:creator>
    <dct:creator>Benjamin Rosenbaum</dct:creator>
    <dct:date>2021</dct:date>
    <note>
      Originally developed by Avery Alder for the prototype of Dream Askew,
      further developed in partnership with Benjamin Rosenbaum for dual
      publication with Dream Apart.
    </note>
  </resp-stmt>
  <style>
    <style-name>narrativist</style-name>
    <style-note>collaborative worldbuilding</style-note>
  </style>
  <games>
    <game>
      <dct:title>Dream Askew</dct:title>
      <dct:source>https://buriedwithoutceremony.com/dream-askew</dct:source>
      <scope players="3-6" session-time="3-4 hours" campaign="false"/>
      <dct:description>
        A game about a close-knit group of queers forming an enclave on the edges
        of a society falling apart.
      </dct:description>
    </game>
    <game>
      <dct:title>Dream Apart</dct:title>
      <dct:source>https://buriedwithoutceremony.com/dream-apart</dct:source>
      <scope players="3-6" session-time="3-4 hours" campaign="false"/>
      <dct:description>
        A game about Jewish survival in a fantastical reimagining of the
        Eastern European shtetl.
      </dct:description>
    </game>
  </games>
</rpg-system>

Tweet et al. (2000). The d20 System.

Download ttrpgml-0.1-example-2.xml

<?xml version="1.0" encoding="UTF-8" ?>
<rpg-system
  xmlns="https://dmoles.info/ttrpgml-0.1"
  xmlns:dct="http://purl.org/dc/terms/"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="
    https://dmoles.info/ttrpgml-0.1 https://dmoles.info/ttrpgml-0.1.xsd
    http://purl.org/dc/terms/ https://www.dublincore.org/schemas/xmls/qdc/2008/02/11/dcterms.xsd
  "
>
  <dct:title>d20 System</dct:title>
  <alt-title type="abbreviation">d20</alt-title>
  <identifier type="wikidata">Q284471</identifier>
  <dct:source>https://web.archive.org/web/20040414045127/http://www.wizards.com/default.asp?x=d20/article/srd35</dct:source>
  <scope campaign="true">
    Originally intended for ongoing campaigns with a party of 3-6 players
    and one game master (the "Dungeon Master", or "DM"), d20 games have
    been adapted to solo play, one-shot tournament play, and other variations.
  </scope>
  <dct:description>
    A simulationist, dice-based system with a core mechanic based on rolling a
    20-sided die, applying various situational modifiers, and comparing the result
    to a target value.
  </dct:description>
  <resp-stmt>
    <dct:creator>Jonathan Tweet</dct:creator>
    <dct:creator>Monte Cook</dct:creator>
    <dct:creator>Skip Williams</dct:creator>
    <dct:date>2000</dct:date>
  </resp-stmt>
  <rights>
    <copyright>Copyright 2000 Wizards of the Coast, Inc.</copyright>
    <rights-uri>http://opengamingfoundation.org/ogl.html</rights-uri>
    <rights-uri>https://creativecommons.org/licenses/by/4.0/legalcode</rights-uri>
    <note>
      Originally licensed under the Open Gaming License 1.0a. Some later versions are
      dual-licensed under the Open Gaming License and Creative Commons Attribution
      4.0 International.
    </note>
  </rights>
  <style>
    <style-name>simulationist</style-name>
  </style>
  <games>
    <game>
      <dct:title>Dungeons &amp;amp; Dragons</dct:title>
      <edition>3rd</edition>
      <dct:description>
        The third major edition of the long-running Dungeons &amp; Dragons franchise,
        and the first published by Wizards of the Coast.
      </dct:description>
      <resp-stmt>
        <dct:publisher>Wizards of the Coast, Inc.</dct:publisher>
        <dct:date>2000</dct:date>
      </resp-stmt>
    </game>
    <game>
      <dct:title>Pathfinder</dct:title>
      <dct:description>
        A standalone game developed to be compatible with material published for
        Dungeons &amp; Dragons 3.5.
      </dct:description>
      <resp-stmt>
        <dct:publisher>Paizo Publishing</dct:publisher>
        <dct:date>2009</dct:date>
      </resp-stmt>
    </game>
  </games>
</rpg-system>