Designing Game Worlds



Coherent game-world-designs for open worlds through procedural generation techniques

#StudioIntegrativeDesign #Master-Thesis

"Open World Games" have potential for countless hours of exploration and gameplay due to their huge game worlds. Procedural generation of game content by computer software is therefore becoming more and more important as a design technique. Using such techniques may cause problems in the coherence of the worlds that adversely affect the game experience.

In his master thesis, Mihajlo Nenad deals with the development and design of an open-world game. The aim of the work is to develop and apply concrete methods for the generation of coherent visual languages in open-world games (and their components) using the prototype GenoTerra.

Generative design is a new possibility for creating coherent visual languages in open-world games

Generally, large teams of trained specialists work on open-world game productions, design and program the game content for a meaningful way of integration. An alternative to the traditional design of open-world games is the procedural generation of content by computer software. In doing so, procedurally generated content does not automatically lead to more coherent content. However, it can help the designer to develop a visual language and successfully establish it as an overall aesthetic in the game.

Procedural Generation in Games (PCG) is the game content created by a computer on the basis of a set of rules programmed in the first instance by humans.

«In other words, PCG refers to computer software that can create game content on its own, or together with one or many human players or designers. A key term here is “content”. In our definition, content is most of what is contained in a game: levels, maps, game rules, textures, stories, items, quests, music, weapons, vehicles, characters, etc.»

Togelius Julian, Shaker Noor, Nielsen Mark J.: Procedural Content Generation in Games. A Textbook and Overview of current Research. Springer (2016) S. 1

Procedural generation is becoming increasingly important and can be used, for example, No Man's Sky, are now used for the generation of entire game worlds. It is used where content does not need to be loaded at the beginning of the game, only when the player is aware of or interacts with content. This procedure optimizes the computing power and regulates the computer-internal resource handling.

In contrast to the manual design process, which Mihajlo Nenad also sees as generation, procedural generation has the advantage of coming into effect only shortly before the moment when the design result in the game is important.

The Game "Rogue" (1980) is considered to be one of the first games that took advantage of procedural world generation. From today's perspective, this world looks graphically poor. The dungeons that the player (@ -symbol) researches (crawl), consist of text symbols like the rest of the elements. The score can not be saved in the original title because the game world is regenerated procedurally each time. One way to get around this today is to use the same "seed" or save it.

A "seed" forms the start value for the generation. The seed can have different forms. Examples of a seed are:

Integers: 1, 2, 24, 678 ...

Decimal numbers: 0.1, 0.5, 7,934 ...

Letters: a, b, C, D ...

Several letters: abc, hello, ThesiS

Data / time: 30.05.2018, 23:15:30

This seed acts as the initial value for a set of rules that a human has previously programmed on a computer. One such rule for a generated rectangle might be as follows:

Rule 1: Seed + Seed2 = width of a rectangle

Rule 2: (Seed - 1) + Seed2 = Height of a rectangle

Rule 3: if seed> 3 = blue rectangle

Thus, content can be generated by the computer autonomously. Such content may take on complex forms, depending on the programmed rules. In addition to the visual form of objects, stories and properties of game content can be generated procedurally in the same way.

Game vs. Play

If a game lacks concrete rules and builds on pure gamer's knowledge in the digital space, a «game» is referred to as «play».

The spanish philosopher, literate and literary critic George Santayana describes the term «play» in his work «The Sense of Beauty» as follows:

«Play is whatever is done spontaneously and for its own sake.»
Santayana, George: The Sense of Beauty. Being the Outline of Aesthetic Theory. New York: Dover Publications, Inc. (1955) S.19

David O’Reilly, a contemporary director of animation films, convinced large strata of the gamer- and non-gamer-scene alike with his title Everything [3] from april 2017.

«Everything ist ein interaktives Erlebnis, das dich alles sein lässt was du sein möchtest. Egal ob Tier, Planet, Galaxy. Reise zwischen dem Mikro-, und Makrokosmos hin und her und erforsche ein grosses, miteinander verbundenes Universum ohne verpflichtende Ziele oder Aufgaben.» (12.05.2018)


Coherence of imagery is understood in Mihajlo Nenad's work as a coherent (unified) design, a stylized design. A visually incoherent (non-uniform) world usually leads to a less aesthetically pleasing, visual experience of the game.

David O'Reilly writes in his essay Basic Animation Aesthetics on the keyword coherence:

«My central belief is that the key to aesthetics is coherence. In 3d we essentially create artificial models of worlds, I contend that what makes these worlds believable is simply how coherent they are; how all the elements tie together under a set of rules which govern them consistently. This coherence spreads to all areas of a film; dialogue, design, sound, music, movement etc. Together they create a feedback-loop which reaffirms that what we are looking at is true. The human eye wants this aesthetic harmony.»
O’Reilly, David: Basic Animation Aesthetics (2009) S.2

The designer of the game or, in large productions the art director of the game development company, sets the rules of design and constantly checks for visual coherence. Additionally, a designer must of course also take into account the story of the game in his decisions.

Principles of the labyrint

Probably the most significant and obvious scope for procedural generation in game development is where a programmed set of rules in the form of one or more algorithms can, in less time, or much easier, produce more results than human designers do in manual work. Examples of this are projects in which players can apply the same game principle to an infinite number of starting situations. Taking simple, two-dimensional mazes, a program could be written which procedurally under the rule (labyrinth size = X times Y pixels, 1 input, 1 output, 1 path from input to output, Seed = number of aberrations) theoretically can create infinite mazes.

Such maze principles are used in many dungeon games (games in which the player struggles through a dungeon to the finish) in a much more complex form.

The Game GenoTerra has been developed by Mihajlo Nenad with Unity. The procedural generation of the landscape is based on an open-source code by Sebastian Lague.73 The programming language of the project is C # (C Sharp). For the vegetation generation human-agent Proc.Gen is used. The basic forms for any vegetation in GenoTerra were created with the Shape Generator tool, which in a second step were worked out manually to the final asset (game component).

The story of GenoTerra is designed to give the designer the ability to manipulate a game world for visual coherence. In order to make this possible, an earth-like planet was chosen as the scenery to enable a science-fiction setting. When designing this planetary environment, physical conditions can be disregarded and biologically "impossible" beings, i.e. vegetation and landscape forms can be created.

With his prototype GenoTerra, Mihajlo Nenad has attempted to develop a method whereby the advantages of procedural generation can help designers develop faster and easier coherent game or image worlds in open world games.

His master's thesis was awarded the People's Choice Award at the CHI PLAY Conference in Melbourne in 2018. A report on his achievement can also be found in this article in Hochparterre.

Video game prototype GenoTerra


Dr. des. Ralf Michel

, Studio Integrative Design

Réne Bauer

, Head of the MA Game Design programme, ZHdK