At day four of Gamescom 2020, The Outer Worlds: Peril on Gorgon DLC director Carrie Patel shared pre-release footage of a side quest in this part of the game. Take a look above.

The Outer Worlds’ first expansion will be made available on Xbox One, PlayStation 4 and PC on 9th September, and as previously confirmed by Private Division, is also on the way to the Nintendo Switch – but doesn’t have a release date yet.

Here’s a more recent reminder of this, along with another tweet that the publisher is still hard at work on a patch for the Nintendo version of the game:

Would you be interested in trying out this DLC in the Switch version of The Outer Worlds? Leave a comment down below.

The following blog post, unless otherwise noted, was written by a member of Gamasutra’s community.
The thoughts and opinions expressed are those of the writer and not Gamasutra or its parent company.

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“Putting into play” originates from the site Narrative Construction, whose goal is to offer a hands-on approach to the design of an engaging and dynamic game system from a narrative and cognitive perspective. The series illuminates how our thinking, learning, and emotions interplay when the designer proceeds from scratch to reach the desired goal of a meaningful and motivating experience. 

Before shifting to interactive media, I wrote story arcs for films and television series. The technique of scriptwriting was to follow your gut, establish a conflict, take it to a climax, and end it with a twist. The receiver’s engagement was built into the dramatic story structure, which meant that focus was laid on the character’s motivations, relations, and behavior. As long as the audience stayed seated and the ratings were good, work continued as usual.

Since my gut was what motivated me to realize new experiences and feelings through a tool, I didn’t look at the change of media as anything other than a natural act of using a new tool. However, when asked to write a canonic story for a game plot like a film, I felt my gut protesting.

Why change tools if it wouldn’t give me a chance to explore new possibilities?

The problem with the gut is that it doesn’t come with an answer. It can just leave you there with an awkward feeling that things don’t make sense. The good thing about the gut is that it’s loyal as hell. It can just turn itself into a mood and linger in your memory as a reminder until your brain works out the answer. The effectiveness of your gut can be improved if you get into the practice of backing it up with a drive state of curiosity, which helps to make sure you don’t miss anything that can be useful to the creative process (see Part 6, Putting into play).

Over the years of game development, it has been tangible to those working with narratives that something doesn’t make sense by how the narrative is conceived as a canonic story from other media. For example, you would never hear someone asking you to construct your story like a video game because video games are considered to be what stories aren’t – interactive. And if you get to work with game productions as a writer or narrative designer, it is not given you will be able to work with the development of the parts that are considered to be gameplay related, such as the mechanics and systems.

The game and a narrative designer Chris Bateman says in an article about the understanding of the narrative craft in the game industry:

“Narrative design is “one of the toughest crafts in the whole of video games — made even tougher by the fact that most developers don’t even think that it’s part of their process.”

How come the narrative isn’t a part of the process yet? Haven’t we got over the linearity versus the interactivity debates? Or has arguing about story versus game exhausted us enough to accept it as a fact?

But what if the narrative is more than the parts, the story, and the medium?

Fitting the narrative within games

Since the narrative is fundamental to the cognitive process, being intrinsically connected to our learning and understanding, which permeate the entire process by how you are giving meaning to the parts that are to be presented before the receiver’s senses. Today, it would seem that the game industry has created its own narrative about the narrative.

Ever since the game industry built up speed to its production of story-driven games, intense work has been in progress to make the narrative fit within games. We have now become so used to the narrative being adapted to games that the craft of adaptation has earned its own terms: firstly, converting, which means redesigning the existing storyline of a film or book to fit a video game. One example is the James Cameron moving picture Avatar currently being converted into a game. Secondly, the term merging refers to the craft of making a dramatic story structure fit with the gameplay.

The craft of fitting the story to games has even earned its own genre – the so-called narrative- or story-driven games. The genre is so established that if you claim there are other ways to understand the narrative, people tend to say “I like stories in video games”, as though you were about to remove the fish from the chips.

Since the narrative has turned into something you like or not, it has also become an element you choose to have in your game or not. Associating the narrative with large-scale AAA productions, making a narrative-driven game is even considered an economic risk. This conception of the narrative also rubs off on writers and narrative designers as being something you may either need or not as opposed to programmers, graphic artists, level- and game designers who are necessary.

By looking at the narrative as being a choice, it isn’t strange that the narrative is sometimes considered as being a part of the process and sometimes not.

Bateman suggests that instead of thinking of the story as “the other side of the coin in games,” one should “think of story as one more game system.”. To bridge the gap he proposes an exchange of techniques and experience between conventional writing and game design.

Since I am at the final sprint of Putting into play, which treats the narrative construction of meaning and how emotions assist the design of an engaging and dynamic game system, I intend to take Bateman’s call and add my part to uniting the systems (and minds). As I have one foot in conventional writing, and the other on in game design, I will take you on a trip to find the hidden art of pacing, which means we will trace back to where the core of engagement and motivation resides.

As in previous sections, I will provide a cognitive and narrative approach to the design of an engaging and dynamic game system from a hands-on perspective on the organization, arrangement, and direction of the thoughts and feelings towards the goal of what the receiver should experience or feel.

Tracing the hidden pacing of engagement 

The first time I came in contact with pacing was at a meeting to discuss a playwright at the dramatic department of Stockholm City Theater. Instead of speaking in standard terms about scenes and characters, they turned the playwright into a music piece. The characters’ interactions by how they talked, moved, and behaved were translated into terms of volume and tempo. Using rhythm, they defined the timing of when elements occurred and how long they lasted, and how far from each other they were as to appear again.

First, I was confused and wondered when they should get to the point. Afterward, I was amazed by how it made perfect sense of how words and music/sound connected.

It was not until I started working with game design that I got the opportunity to experience the art of pacing as a feeling of rhythm again. Then it was from the perspective of how you provide and withhold meanings to engage and motivate the receiver’s thinking. It was also then the gap between conventional writing, and game design became visible by how the story structure worked as a method to access the pacing of actions from the receiver’s perspective.

By breaking down the story structure and pacing out the content across sequences so as to meet the receiver’s building of experiences and engagement, you combine the contrasts of tempo (fast/slow) and intensity (strong/soft). In relation to actions, intense combats are followed by peaceful puzzles or an exploration of the world while gathering objects. It was also here, in the craft of pacing out the content through missions, levels, environments, and worlds, you could find the systems of quests, dialogue-trees branched storylines and cinematic that writers and narrative designers are usually in charge of.

Since pacing is at the heart of conventional writing and game design, which rhythm and tempo accommodate the core to the engaging and motivating forces, I will start by bringing on the dramatic story structure to see where the core resides that connect structures and crafts.

               

Since the whole idea with the art of pacing is to trigger the engaging and motivating forces, which “tricks” by how you entice curiosity shouldn’t be noticed by the receiver. The problem, though, is if the core to the pacing is hidden to the constructor.

The dramatic story structure (also known as the three-act structure) is very good at appearing as if it shows where the hidden engine to the pacing resides by how the acts, turning-points, and conflicts capture an overarching rhythm. At first sight, the structure seems to correspond very well to the idea of how the feeling of being aroused goes up and then down. The structure also hints at converting the rising and falling actions into components that could fit the interactivity of a game.

But as the story structure leads to focus on the development of the characters’ motivations, relations, and behaviors while a gameplay’s structuring concentrates on the receiver’s actions. When taking a closer look at the dramatic story structure as to ask whose actions are actually rising and falling, the structure veils some essential parts that concern the engaging and motivating forces to be from the receiver’s perspective and position. These forces contain the receiver’s feelings, experiences, and expectations brought by the overall rhythm, which captures the core of a mood that follows the receiver after the movie or game ends. This core of the mood works as a drive, which desires encourage us to relive the experience and feelings, which can be noticed when we express appreciation to a specific genre or style (but it can also generate the opposite, which we will get to when looking into balance and control).

When making use of a story structure in the writing and designing of engaging and motivating experiences, you need to look beyond standard features of the dramatic story structures to access the motivating forces that form the core to the mood. The reason is you want to release the thinking and emotions from being framed by the end-state of a structure. As we go, you will see how the liberation fits very well by how the style of the game´s mechanics and systems work.

An example of a core to a mood that is based on the players´desires from earlier games can be found embedded in the mechanic of The Last Guardian (see Part 1, Putting into play, with interviews with Fumito Ueda). The forces constituting the core of a mood were collected from the relation between the player and the girl in Ico, and the bond between the player and the horse in Shadow of the Colossus that were transferred to the boy (the player) and the creature Trico in The Last Guardian.

      

                           Shadow of the Colossus, Team Ico, Sony Interactive Entertainment

Narrative systems

To discern the core of mood which captures the forces of the engaging and motivating drive, I will get underneath the story structure and remove the standards of start, end, acts, turning points, and conflicts and replace them with an engagement and duration-axis.

              

To explain how the engagement and duration-axis work, I will introduce the narrative systems behind the act of stripping the story structure in the first place.

The narrative systems are not the story but the systems that assist the structuring of patterns, which are based on the narrative principles of logic, time, and space (which I will return to later as they can explain what causes gaps).

The narrative keys of perspective, position, and goal presented in the previous section (see Part 6, Putting into play) represent the three narrative systems that constitute the cognitive process behind the creation of meaning. The systems that originate from David Bordwell’s studies (Bordwell, 1985), also constitute the base to the method Narrative bridging (Boman, Gyllenbäck, 2010), which I am using in various forms depicting the hands-on approach to the design process (can be recognized from its color scheme).

• The narrative system of syuzhet translated as plot (which term I will use) defines the constructor’s perspective and position in the arrangement of causal, spatial, and temporal networks. The numbers of techniques on plotting are many, and my intention is to give you the base. The plot is not the story but the patterning of a story, or the patterning of gameplay (which I will get to later). The numbers of patterns that can be plotted are infinite. An example of one pattern is the canonical story format (exposition, complication, outcome). The pattern is a result of a long Western tradition of analyzing the assumptions of a canonic story. The canonical story format works as a template of developing story structures and where the three-acts story structure is just one variation of the template.
• The plot system can’t exist without the other system of style that mobilizes components and techniques provided by the medium and vice versa.
• The plot and style systems prepare for a third system: fabula, which represents the receiver’s perspective in the interpretation of the plot and style.

The reason why it may seem unclear from which perspective the rising, falling action, and the climax of the dramatic structure are taking place is that the structure doesn’t define the systems of style or fabula. This is also why I have toned down the rising and falling actions, and the climax, for the time being as they will make sense when we get to the gameplay structures.

The narrative keys assist the change of perspective/position, and the goal captures how the plot and style convey the desired goal/outcome of what the receiver should feel or experience from what is presented before his or her sense (see Putting into play, Part 4 and Part 6).

Since each narrative system contains two perspectives –  the constructor’s and the receiver’s – as we go, it will be easier to understand how the unfolding of plot and style affects the experience of the receiver if you have picked the “right system”. To “pick the right system” I will let the team that was introduced earlier (see Part 6) illustrate the two main perspectives and positions.

The team constructors represent the style and plot and the team interpreters represent the receiver’s interpretation of the plot and style.

       

The way our mind processes information creates a common denominator and bond between the teams (see Part 6). From the perspective of the constructor, to access the core of mood where the experiences and expectations reside, your approach to the development of an engaging and motivating experience should always be to consider the possibility offered by the receiver’s (interpreter´s) ability to think, learn and create meaning.

               

Thus, the meaning created by you as a constructor will be converted into experiences and expectations by the receiver (interpreter).

              
The core cognitive activities mentioned above have been presented throughout this series and are based on the 7-grade model of causal cognition (Gärdenfors, Lombard, 2017). Here, the model helps to illuminate the process of how our thinking leads to the drive-state whereby we pick up meanings from what is presented before our senses and store the feelings of these experiences in memory.

These elements compose the dynamic forces behind the narrative vehicle of meaning making (see Part 4, Putting into play), which provides a possibility to engage and motivate the receiver (the interpreter) along the duration axis.

In order to meet the receiver’s (interpreter´s) capacity to process causal, spatial and temporal links in the creation of meaning, I will replace the turning-points and conflicts with the minimum of data needed to trigger an emotional effect to the engagement and duration-axis – which is cause and effect.

               

How to play on the causal keys of plot

Since it is an established fact to writers and designers that the pacing of engagement of cause and effect is similar to the craft of composing sound and music. This can be noticed by the shared vocabulary of musical terms such as rhythm, tempo (beats per minute), tone, and theme.

If you imagine the green dotted lines of cause and effect above as piano keys or audio tools. When striking the causal elements within a duration of time, you give tone and mood to the experiences and expectations. Tone and mood are what we commonly call themes that capture experiences and feelings.

What fascinated me the most when experiencing my playwright as a music piece was how the style of the theater wasn’t mentioned. The explanation for this can be found in the culture to not precede the director’s and actor’s artistic work to interpret and design (gestalt). It also gives us a hint of why writers are expected by routine to keep a low profile so as to allow for the next level of artists to step forward and finalize the concept. However, the experience gave me insight into how the plot constitutes a system that, independently from style, creates a causal rhythm, which can be applied and moved between media.

I would like to share this insight as it gives you the basic techniques to the pacing and balancing of the plot by how the rhythm and tempo form a dynamic pattern. To avoid being too abstract when showing you an example of how they utilized music terms at the theater,

– I will “play” a theme on the keys of cause and effect that generates the excitement of a classical story structure, which means the cause and effect will be presented within the frame of a start and an end.

– I will define the goal by setting the duration within the time frame of a movie. By doing this, I also describe the style of the medium that mobilizes the theme.

To express strength, rhythm, and tempo, I will start using the musical terms that apply to the dynamic elements of loudness and intensity (strength), i.e., volume:

– Forte, is loud/strong

– Piano is soft

To give you a sense of how the plot works independently from media, I will start with a music piece before moving to the plot pattern of a classical story structure.

In the illustration below, the musical terms are depicted by the first punch on the keys of cause and effect that creates a forte (1), which is followed by a piano (2).

               

If you haven’t heard about the music piece called Carmina Burana, I am pretty sure you have heard a choir singing: “O Fortuna” (if unsure, check this link on Youtube).

The song starts with a punch of a kettle-drum and a choir singing out loud: “O Fortuna.” (1). By moving on forward on the duration-axis the forte changes into a piano (2). Then the dynamics gradually build up an overall rhythm along the duration-axis towards the climax (3 and 4) and return to the same strength as at the beginning (5) keeping the forte until the end (6).

The same pattern that is reflected in the description of the song can be seen in the pacing of cause and effect in a movie with a theme intended to create the kind of excitement we know from a classical story structure.

Based on the same diagram as above, the forte is illustrated by a global conflict (1). Next after the forte, the daily life of activities and internal conflicts in a village is presented with a piano (2). Next, the engagement of the villagers builds up the cause and effect that raise their awareness about the global conflict (3). When the villagers realize the inevitable by how cause and effect unfold, they will put aside their problems (4) – at least that is what characters usually think – to battle the global conflict (5). But the villagers will also have to fight their internal disputes at the end (the so-called resolution) (6).

The contrast between forte and piano in music constitutes a sudden dynamic change that even has its own musical term: fortepiano (fp). In your crafting of engagement, it is the contrasts and nuances of the components causal relation that create the dynamics. This explains how the plot conveys contrasts between the forte from the global conflict (1) and the piano from the daily life in the village (2), in which dynamic forces increase engagement when they change along the duration axis.

If you would like to guess which classical story I’ve depicted, now it’s the time.

The diagram, which shows the composition of Carmina Burana and the plotting of cause and effect of a classical story structure, gives us the pattern of the movie: The Lord of the Rings

To compare the feelings brought by the plot pattern, you can check the song while bringing memories of mood from the movie. As I didn’t mention the tempo you can notice how the forte (1) has a slow tempo and the piano (2) is conveyed with a rapid tempo.

As you can see, the dynamic changes of contrasts and cause and effect conveyed by the plot are united in either medium through pacing. The variations of dynamics in a pattern can be noticed in the canonical story format by how cause and effect are conveyed by style. For example, in the book, the introduction is more “piano” than “forte,” as Tolkien begins by presenting the hobbits’ life, only to let the global conflict gradually sneak upon them.

How plot and style coexist

The engagement and duration-axis make it easier to discern the dynamics between cause and effect by recognizing how plot and style coexist. It also gives us a hint about how writers and designers are narratively connected through the pacing of rhythm and tempo.

To identify the possibilities offered by plot and style, I will demonstrate how the systems connect by engaging the team constructors in the making of a sound effect.

                           

Based on the principles behind the dynamic contrasts of cause and effect, the constructors will make sound effects of a fortepiano (fp) that is added to the first sequence of the plot (1).

              

The dynamic changes from volume (fortepiano) the sound effect of an explosion (7) followed by silence (8) is well known from films and games. The dynamics of cause and effect of the sound effect also reveals the third system, fabula, by assuming that the hearing senses will pick up the cues of causal and temporal links – illustrated by the engagement and duration-axis.

As you can see, it is tricky to depict a sound effect without referring to the intention of what the receiver should experience or feel, which shows how plot and style correlate with the systems of fabula. But if we hold on to the interplay between plot and style, you can see how the contrasts and nuances of the components’ causal relation create dynamics. A loud sound may have a slow tempo, and vice versa, a soft sound may have a higher speed.

The rhythm, tempo, and volume flow through every single element from the pacing and balancing of plot and style, which causal network brings the harmony of cohesiveness to the experiences and feelings. Dynamics of causal contrasts can transmit to the stature, movements, and behaviors of objects and characters. An example of a dynamic causal effect can be from a slow movement of an object as the old wooden carriage at the start of The Elder Scrolls V which takes people (including the player) to their execution. Conveyed by animation, sound, and mechanics, the style dynamically mobilizes the plot pattern from pacing tempo and strength.

An example where one might not even see how the pacing of dynamics convey style is in the characterization of the tall human Gandalf and the little hobbits in The Lord of the Rings by how causal network between the stature, behavior, and movements gradually deepen the engagement over time.

           

The causal contrasts between the size and power of Gandalf and the little hobbits play a significant role in the building of rhythm that conveys a mood. By showing a tall human Gandalf who possesses power (7) in relation to the global conflict (1), and then moving on the duration axis to the village (2) and the small hobbits (8), the beat of the meeting between Gandalf and the hobbits (9) reassembles a causal dynamic effect of a fortepiano.

The pace of engagement is gradually built up by conveying the dynamic effect from the fortepiano (1, 2, 7, and 8) to flow through the tempo of movements and behaviors of the characters. The tempo from Gandalf’s big and slow steps and the hobbits’ rapid steps to keep up with Gandalf, and Gandalf’s awareness about the global conflict (1) and the hobbits unawareness, convey a dynamic depth to the behavior through the pacing of plot and style.

The causal contrasts play a crucial part in the pacing and balancing of engaging and dynamic experiences. How the contrast of tall/little, big/small, and rapid/slow strike a chord within the receiver is due to the causal elements that trigger the core cognitive activity of comparing. Once you get someone to compare, the behavior and movements of the receiver´s meaning making will become a part of the overall rhythm. This rhythm constitutes the core of the dynamic flow, which plot pattern you can move from one medium to another.

For example, the same causal contrasts which flow through the stature, behavior, and movements of the hobbits and Gandalf can also be found in the relationship between the little boy and the huge creature Trico in Fumito Ueda’s video game The Last Guardian (see also Part 1 and Part 4).

     

                         The Last Guardian, by gen Design, Sony Interactive Entertainment

How the dynamics between the boy and Trico in The Last Guardian constitute the core of the game’s overall rhythm is something I will return to in the next parts when adding the last narrative system regarding the receiver’s interpretation of the plot and style.

By uncovering the coexistence of the narrative systems of plot and style, you can recognize how conventional writing is more than the craft of creating a story according to a particular structure. Without referring to a medium or pattern, the technique is based on the pacing and balancing of causal, spatial, and temporal links that trigger the receiver’s engagement and motivation and enhance emotions.

If you have balanced the narrative systems of the plot and style well in regard to what the receiver should experience or feel, you will arrive at a more persistent state of a mood. By arriving at this point, you know the experiences you have built have engaged the motivating engine of learning that will turn the meanings into expectations and desires. The result from your building constitutes the core of a mood that stays in the receiver’s memory. When continuing tracing back to the heart of where the engaging and motivating forces reside, it is the mood we are aiming at as it captures the emotional desire to understand and learn.

With the help of the last narrative system which concerns the receiver´s meaning making, we will look into story and gameplay structures in the next part to discern how the motivation comes into play in the balancing, pacing, and controlling of engaging and dynamic forces in video games. And, of course, you will see more from the hobbits as to understand how the rhythm and mood make us bond with those furry footed Middle Earthier and how the dynamic forces can be applied to the pacing and balancing of The Last Guardian.

Until next time, stay curious and safe.

Katarina

Illustrations by Linnea Österberg

References:

Boman, M., Gyllenbäck, K.,  (2010). Narrative bridging. Design Computing and Cognition ’10. Edited by John S Gero. SpringerLink. pp 525-544

Bordwell David (1985). Narration in the fiction film. Methuen.

Gärdenfors, P., Lombard, M., (2017). Tracking the evolution of causal cognition in humans. In the Journal of Anthropological Sciences 95. p.219-234

Glossary to music terms

Return to:

Part 1 Putting into play – A model of causal cognition on game design
Part 2, Putting into play – On narrative from a cognitive perspective I
Part 3, Putting into play – On narrative from a cognitive perspective II
Part 4, Putting into play – How to trigger the narrative vehicle
Part 5, Putting into play – On organizing thoughts and feelings
Part 6, Putting into play – On organizing engaging and dynamic forces

Or visit Narrative Construction:

Part 1 Putting into play – A model of causal cognition on game design.
Part 2, Putting into play – On narrative from a cognitive perspective I
Part 3, Putting into play – On narrative from a cognitive perspective II
Part 4, Putting into play – How to trigger the narrative vehicle
Part 5, Putting into play – On organizing thoughts and feelings
Part 6, Putting into play – On organizing engaging and dynamic forces

A short guide to the 7-grade model of reasoning

An introduction to Narrative bridging

The following blog post, unless otherwise noted, was written by a member of Gamasutra’s community.
The thoughts and opinions expressed are those of the writer and not Gamasutra or its parent company.

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Quite often artificial intelligence is in control of so many elements of our favourite video games, but we seldom take notice and take it for granted. An AI tool or system can be running in plain sight, providing a critical element of the game that players are largely unaware of until it starts to go wrong. Let’s take a look at a fantastic example of this found in the popular city-building simulator Cities: Skylines. In this article, we’ll take a look at the traffic and navigation systems that run in every city, how citizens go about their day-to-day routine and how developers Colossal Order sought to address the traffic jams that can easily emerge.

About the Problem

Released in 2015 and published by Paradox Interactive, Cities: Skylines is an open-ended city-building simulator where players are responsible for many aspects of modern urban planning. This includes establishing city zoning, utilities such as water and electricity, establishing zones for residential, commercial and industrial growth, public services such as schools, fire services and law enforcement, all the taxation that is required to pay for it all and – critically for this episode – road placement and establishing transportation services within the region. Colossal Order, having achieved success with the Cities in Motion series had sought to expand into a full city building title, a sentiment that at that time Paradox Interactive did not share. However, 2013 saw a gap emerge in the market courtesy of the latest entry in the beloved SimCity franchise from Electronic Arts. The game came under intense criticism at release with players posting screenshots and videos of cities not behaving as expected. And while the issues raised were numerous, there are two critical points we are exploring in this piece.

First, the traffic simulation in SimCity was highly problematic. Traffic would often bottleneck, creating massive jams that seemingly never resolved themselves. Meanwhile, should the play attempt to rework junctions to enable better traffic flow or add public transportation this often proved to be more a hindrance than a help. Secondly, the citizens in SimCity did not behave as expected. While it was anticipated that the sims would live their pre-determined lives – working jobs and living happily in their homes – in reality, they lacked any individuality. Sims would leave the house in the morning, find the nearest job available in the city and then after the working day, they didn’t necessarily go back to the house they left that morning. Instead, they simply go to the nearest vacant property. While this is undesirable it seems slightly innocuous, until you realise how big an impact this had on the already troubled traffic systems as well as the actual behaviour and economy of the cities themselves.

While SimCity sought to address this through numerous patches, it never really coalesced at a solution that players were happy with. However, Cities: Skylines when released satisfied many of the features that players sought from its competitor. And as we’ll see in a moment, it not only tracks the passage of every vehicle through your city’s road system, but your citizens will go about their daily business as one would expect. That said, it still suffers from traffic congestion issues.

Now before we get into the intricacies of this problem and how it is tackled in Cities: Skylines, it’s important to acknowledge that this isn’t just an issue that plagues video games, but the real world too. Traffic management systems in the real world are highly complex and incredibly expensive to research and develop. These systems have to manage signalling, traffic flow and congestion, tracking and responding to accidents and other incidents on the road such as spillages, damage to the road or faults emerging in signalling systems and CCTV cameras that used to provide oversight. There are efforts to employ artificial intelligence to handle the complexities of real-world traffic management, but it is far from a solved problem at this time. Hence, it’s understandable that as city-building simulation games seek to become more and more realistic, the challenges that developers face will rise accordingly.

How Citizens Work

First let’s talk about the citizens, how do they work and what impact are they going to have on the traffic network. Each citizen in Cities: Skylines has information that is used as part of the city simulation. This includes:

• Their name.
• What level of education they have.
• Their residential address.
• Their place of employment or education if they have one.
• Their overall level of happiness.
• Current activity, including any destinations they are currently headed towards if they’re travelling around the map.
• Their health.
• Their wealth.
• References to familial relationships and what other citizens are related to them.

Each of these features impacts the game in different ways. Levels of education influences what types of jobs they take on, the performance of these businesses and the value of residential areas. Meanwhile, happiness is shown to the player and gives a barometer for how well you’re performing, given there may be services these citizens require, such as healthcare or utilities that they feel is lacking or the job opportunities in the region aren’t up to scratch. But perhaps what’s most influential on citizens behaviour moving around the map is their age. While a citizen does have a numeric age, this isn’t exposed to players by default, but the key part is that they live their lives in five stages:

• Children, where they start going to nearby schools if there is capacity.
• Teens, who go to high schools if there is space.
• Young Adults, who either attend university or get a job if they can.
• Adults, who not only move out of their current home and into a new one if they can, but will also settle down and start their own families.
• Seniors, where citizens retire and no longer go to work but still use city services and commercial businesses.

This has a huge impact on the transportation network, given kids are going to school, adults are either at university or in a job and pensioners are still active in their senior years. Some of these citizens will be in their own car while others use public transport. And this is a very difficult balancing act, given not only will your city grow if you’re doing your job right, but citizens age at an incredibly fast rate, with their average life expectancy of around six in-game years.

How Are Roads Built?

So given we have so many citizens moving around, how does the road system work? Under the hood, roads are modelled as a collection of nodes. Two nodes connected to one another is a segment, providing both start and endpoints. Your average road in Cities Skylines is actually multiple segments glued together, given a segment has a maximum size. Each node in a segment is known as a control point, this provides start and positions for roads, as well as the intersection with other roads creating junctions. Each segment of road stores information about itself, including what type of road it is, how many lanes it has and what types of lanes these are. This all become useful when a citizen wants to travel between locations.

Now this information extends to sidewalks too, which operate on a slightly different system, given they can be elevated or tunnelled to go over or under traffic and crosswalks are established when building them alongside roads to enable pedestrians to cross. All of this information comes into play when a citizen makes the decision to travel to a destination.

Building a City in Motion

Having citizens move around in Cities: Skylines is – by the developers own admission – the single greatest challenge faced during development, resonating with the issues that plagued Sim City. Given it is arguably the one system that any player who spends more than 10 minutes in the game will come to interact with, hence ensuring a basic level of functionality and avoiding some of the more gnarly edge cases was paramount. To that end, not only did Colossal Order rework this system several times over, but as we’ll see in a moment, some elements that players might want to see were actually removed because it only made the problem worse

When a citizen decides they want to travel, they use all of the available information about the cities transport infrastructure: including the roads, sidewalks, crossings, public transportation routes and available vehicles and will find the fastest possible route to their destination. Hence the node system within the roads and sidewalks is searched through to find a valid path. This actually factors in numerous elements based on the citizen involved and the local geography. If a citizen owns a car, they will attempt to drive it. If they don’t have a car, they’ll not only check for a valid path on sidewalks but also factor in whether there is any public transportation that can speed up that process. In some cases, there are strict rules on how this can operate: specific buildings such as hospitals and fire departments will enforce the use of ambulances and fire trucks respectively rather than a firefighter taking a bus with a bucket of water as your home turns to ash. Meanwhile, pedestrians cannot walk on highways and hence if they don’t have public transportation options and sufficient sidewalks to get them to their destinations, they’ll resign themselves to defeat. Colossal Order has never outright stated what they’re searching algorithm is. However, given the rich data laced throughout the road network, it would not be surprising to find a modified version of A* or Dijkstra’s that achieves the desired effect.

The resulting system is actually quite remarkable that a character can make this level of nuanced decision making, especially at this scale. Given a pedestrian can easily walk and take multiple forms of public transportation in order to get to their destination. The destination they want to visit can vary and while they will prioritise going to the primary destination for their life stage – such as school, college or work – they will also go to commercial units such as shops and restaurants, as well as clinics and hospitals.

When a citizen takes a car, it utilises not just the road network topology, but the additional constraints of the road type themselves against the vehicle. This includes the dedicated cycling or bus lanes, as well as the speed limits, the number of lanes and the current congestion level. Provided the system can generate a path through the road network, then the vehicle will begin to drive it. It can also still use the public transportation system. Hence it is possible for a citizen to drive to a metro station and then use that for the remainder of the journey.

In essence, that’s how Cities: Skylines works, but there are several edge cases revolving around traffic, the number of citizens in the city and much more. And we’re going to get into that now, but before I do there are two really important caveats. Firstly, not all citizens are rendered in the city at any point in time. There is a hard limit on how many citizens and vehicles can be simulated on the streets of your city at any given time. Now you might think this is just a rendering issue: in that the game is still simulating all citizens under the hood and you just don’t see it. No, no, no; Cities Skylines outright caps how many citizens can be travelling within the city at any given time. There is a separate system that monitors whether there are available slots for travelling citizens and then allows them to travel once there is space. While the movement of citizens is important for maintaining the economy and their own personal health and education, you the player are not penalised for a citizen being unable to travel due to this simulation cap. The system that oversees this ensures that players are not punished because a citizen is – due to computing limitations – unable to travel to their desired destination. The second caveat is that the traffic you see on the streets is a separate simulation system from the citizen management. When you watch traffic, it’s a collection of thousands of small physics objects that read information from the road network to figure out how to move through it.

So for the remainder of this episode, let’s look at two things: first how the traffic simulation systems work, and secondly, what happens when traffic jams start to occur in the game world.

Watching Traffic

Traffic is handled in a separate simulation system that is actively calculating how to follow the chosen path, the velocity that the vehicle should be going at and preventing collisions. While traffic looks like this smooth and constantly updating process, it’s only rendered that way. The traffic simulation is updated 4 times a second, and the rendering system takes two of these simulation updates to derive movement of the objects on the screen.

When traffic is simulated a vehicle knows the path that it’s been told to go on and they know where on a given road they can drive – hence they won’t drive the wrong way down a one way. Paths through the roads are calculated on a spline using the nodes of each road segment. This allows for tight curves and intersections to be handled as gracefully as possible.

These simulation steps allow for vehicles to calculate whether collisions are going to occur at intersections or from traffic slowing down. Vehicles do recognise traffic lights and will slow down and stop if the lights dictate they can’t travel into the intersection. Meanwhile, to minimise crashes, vehicles check ahead of themselves during the simulation for whether a collision between two vehicles is imminent. This annotates a segment of the road as liable to cause a crash, at which point the distance to the segment is used to decide which vehicle goes first and they move through it on a first-come-first-served basis, each adapting speed accordingly.

But of course despite all of this effort, there are still issues with traffic jams. In part this is to be expected if the player does not build the network sufficiently, but there are other issues that impact the system. So let’s wrap up by talking about what the simulation does and does not do in order to keep it manageable.

First of all, unless something happens that causes a given path to no longer be valid or has been extensively modified, a citizen or vehicle will not change their pre-calculated route. You may think there would be some opportunistic behaviour going on where a character may re-evaluate their options on the fly, but nope, only in the event something happens, that negates the original path. While in some larger segments of the road with multiple lanes that could spread traffic out, you’ll notice they don’t change lane again after moving into the one they originally decided upon – even if that would make sense to do so. Having vehicles change lanes midway through a segment of road was actually something that Colossal Order experimented with, only to later remove because during internal testing, it actually made everything worse.

When traffic builds up, you may see cars sitting idle at junctions and not moving forward, despite having room to do so and that’s often because their paths have determined further issues up ahead and as a result they opt to simply stand idle.

Last but not least, Cities Skylines has a fallback option for when traffic jams are overwhelming. If a vehicle has found itself in gridlock and unable to move, it will actually teleport back to its origin. And the previously mentioned worker system may well stop that citizen from trying to travel again and avoid punishing the player any further. This was a decision made by Colossal Order in order to make the transportation challenge more manageable, given even relatively small cities begin to be impacted by this issue. This decision has actually proven to be contentious among some players, who prefer the challenge it presents and use mods that actively remove the teleport feature.

Closing

Building a city simulation game is incredibly demanding, especially as the granularity and fidelity of the simulation increases. Cities: Skylines is an incredible effort from a team that – at launch – was comprised of only 14 people. But it shows the core tenets of their design from previous games could steer them through to making a game that is now the leading game of its kind on the market. With an entire generation of city planners still working away for hours on end perfecting those road networks, Colossal Order knows this is a problem they need to tackle again in future releases. The issue of the traffic is an ongoing one within the Cities: Skylines community – with some PC players using mods to teleportation or outright replace the pathfinding systems used in the game. Meanwhile, others are happy to leave it as it is and embrace the chaos.

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