Tools for automatization of knowledge on game mechanics and their interrelationships are still lacking. Game design patterns, as proposed by Bjork and Holopainen, seem promising in this area, as they can be represented formally as an ontology. This paper presents our proposal of such a representation, developed using OWL2. We discuss the design of the ontology, and demonstrate how it can be used to conceptualize the design of a classic video game. In the future, the ontology will provide a knowledge base for a new tool for game developers, in order to enable more complex, interesting and emergent game design.
Modern game designers have a multitude of tools for game design and development at
their disposal. Nevertheless, a proper and consistent way of capturing their knowledge
on game mechanics has not been established yet. Nowadays, there is a persistent
need for formally (or at least semi-formally) defined knowledge base for game design.
A partial solution has already been suggested by S. Bjork and J. Holopainen [
A pattern is defined as a description of a part of the interaction that is possible in
the game. The idea refers to the patterns in software engineering [
This paper provides a description of the GDPs' ontology, developed as a basis for a future ontology-based tool for game design and development. The GDPs are more thoroughly described in Sec. 2. The description of the ontology itself is provided in ? Supported by the AGH UST grant.
Sec. 3. To demonstrate how such a tool would work, a design of a classic video game is described in terms of the patterns in Sec. 4, and a sample use case is provided in Sec. 5. Related works are discussed in Sec. 6 and the paper is concluded in Sec. 7. 2
The Game Design Patterns constitute a framework developed by [
In this framework, Instantiating means that one pattern is referring to an area of game play that is more general or abstract to the other: for example, a pattern Score, which refers to the numerical representation of player's performance, often might instantiate Collecting { as it is an action of acquiring game elements that add points to the score. Modulating describes a reverse, in a sense, situation, where a \sub-pattern" fine-tunes the more abstract one { a pattern Privileged Movements modulates a pattern Movement. Potentially conflicting patterns are ones that possibly form a contradiction. For example, a pattern Perfect Information, where the player is provided with complete information about the game state, potentially conflicts with Randomness.
There is a demand for a representation of knowledge more structured than a
loose collection provided by [
The ontology1 consists of a one global GDP class, 38 subclasses and 296 instances. The subclasses are all disjoint. Each subclass comprises of a group of patterns that are related to a certain area of game play. The patterns themselves are instances in the ontology. Each pattern possesses three string-type annotations: a label, a comment with a brief description of the pattern, and an example of a specific application of it (see Fig. 1). Fig. 2 provides a glimpse of a small fragment of the visualization of the ontology.
The relationships between the patterns are described as object properties. Instantiates and Instantiated by as well as Modulates and Modulated by are properties inverse one of another. These pairings have 3026 and 2864 uses in the ontology, respectively. The Potentially conflicting with relation is symmetrical. 1036 uses (potential conflicts between patterns) are specified in the ontology. For all of the object properties, the domain and range are provided by the global GDP class. 4
The game design patterns were developed with two main purposes in mind: for game designing, but also for game analysis. Setting out from a single pattern, and following 1 The full ontology is available on request at author's website, see: https: //www.affcai.eu/doku.php?id=sci:ontology. the suggested relationships, one is able to describe each aspect of the game play. This section provides an exemplary analysis of a classic arcade game, Pac-Man (see Fig. 3).
Briefly speaking, Pac-Man is a game where the player navigates through a maze and collects pills. The goal of the game is to `eat' all of the pills on the level. The player is impeded by four ghosts that chase the player's avatar. For collecting the pills and fruits, the player is rewarded with points that are added to their score.
In this basic description of the game, one can already identify numerous design patterns. Patterns Movement and Collecting reflect the core of the Pac-Man's game play. Score instantiates Collecting, which is instantiated by, i.e., Pick-Ups that can be collected. On the other hand, Collecting modulates Character Development. For a short duration, eating power pills in Pac-Man enables eating ghosts, which can be perceived as a temporary development of the character. Score in Pac-Man will stand in opposition to Save-Load Cycles { the player cannot create save points for any game states to load them later. For a graphical aid of Pac-Man's pattern relations, refer to Fig. 2. 5
The Game Design Patterns Ontology was prepared using the OWL 2 Web Ontology Language, and as such can be further processed, e.g. with the use of SPARQL. This allows (semi-)automatic processing of the developed game project. To provide an intuition on how the design process can be improved by the proposed ontology, a sample query is presented in this section (see Listing 1.1). The use case relates to a situation when a game designer wants to check for potential conflicts in the prepared game design. 1 PREFIX rdf: < http :// www . w3 . org /1999/02/22 - rdf - syntax - ns #> 2 PREFIX owl: < http :// www . w3 . org /2002/07/ owl #> 3 PREFIX rdfs: < http :// www . w3 . org /2000/01/ rdf - schema #> 4 PREFIX xsd: < http :// www . w3 . org /2001/ XMLSchema #> 5 PREFIX gdp: < https :// geist . re / gdp #> 6 ASK { 7 ?subject gdp:potentially_conflicting_with ?object . 8 FILTER (?subject IN (gdp:score , gdp:collecting , gdp:save - load_cycles ) ) 9 FILTER (?object IN (gdp:score , gdp:collecting , gdp:save - load_cycles ) ) 10 }
Listing 1.1. Check if there are any conflicts in a given set.
The query in 1.1 will check if, in a given set of patterns (here Score, Collecting, and Save-Load Cycles), any two of them are in a Potentially conflicting relationship, either as a subject or an object (mind the symmetry of the relation). In this case, the query will return TRUE (see Sec. 4 for explanation). 6
Several similar works regarding ontologies were selected and discussed in the light of the
one proposed in this paper. For starters, MOUDIL [
In this paper, a new ontology for game design patterns has been described. Following the explanation of the underlying concept of patterns in game design, an exemplary analysis of a classic arcade game has been provided. Finally, a detailed characterization of the ontology has been presented.
In order to bring the ontology to the developers, future works include creating
an ontology-based tool. Our main focus are complex adaptive systems, with a special
emphasis on engaging the user's emotion to be the motor of the adaptation. For
a designer of such affective video games, an ontology extended with information
on emotional change's caused by pattern implementation could help to develop an
emotion model of either the player, or the game world itself [