Music of the Urban Commute: Designing Mini Metro’s Soundtrack

A year ago, when Rich Vreeland (aka Disasterpeace) said that the work on his score for Mini Metro (2015) would be around 90 percent coding, not many knew what he meant. At the time, the only insight he shared was that the results of his work would create procedural audio for the subway system management simulator.

When Mini Metro was released with what Vreeland calls an “almost meditative” score, it had a different feel to it than I had expected. The pressure and anxiety that comes with the city-building genre, as experienced in games like SimCity (1989), were minimized by the soundtrack, as well as the train engine sounds, the effects of people popping up in different stations—the general musicality of the environment. It resulted in several hour-long game sessions that felt like only 15 minutes to me. “That was the idea,” said Vreeland. “It was to create music that [led to] a very immersive space that would just allow the player to maybe not be stressed out and that they’d be able to play it for longer.”

The lines themselves have rhythms attached to them, as if they were pulsing

While Vreeland says that now, this was not the initial goal of his work on Mini Metro. Along with the twins of the game studio Dinosaur Polo Club— Peter and Robert Curry—he intended to create a system that would give immediate audio feedback to the player according to what was happening on the screen. If a station was getting too crowded, the sound it would emit would be different than that of a new station being created. “[I was] trying to do my best to make the sounds cohesive with each other but also different enough from each other that you could identify different aspects of the subway system,” Vreeland said.

His dedication to that distinction had a lot to do with the creative process of the procedural audio and how he faced the project with the studio. “When I’m working with code I find that it’s very easy for me to put in really long hours and to work well into the night,” Vreeland said about his routine when working on the game. “[It was a lot of] allowing myself to be influenced by feature creep, the idea that when a new idea comes in and instead of saying ‘Oh, no, I don’t have enough time to do that, that’s gonna complicate things,’ I’ll explore it.”


Fortunately for Vreeland, Mini Metro’s abstract nature allowed for this working process to be viable. It didn’t matter so much that he was working with different rhythms, as each level has its own set of harmonies, meaning they all had an individual “core progression” with multiple rhythms possible within that. In the Osaka level, for example, the fast trains that run on the Shinkansen rail lines have a unique engine sound that Vreeland worked on and explored in an hour-long blog video when he was designing it. “The lines themselves have rhythms attached to them, as if they were pulsing,” he said. “Then also, when a bunch of passengers appear at once, they kind of appear in a fan. Different cities have different sounds for that. And the same for passengers getting on trains.”

The idea was to create a language with the music. One that the player learned through its consistency, which was important in a game that relies so much on its audio feedback. This freed Vreeland up to make small changes that would make sense within the culture of each city. “A level like São Paulo has a slower vibe,” he said. For this, he took from bossa nova, a fusion of smooth jazz and Brazilian samba, which was very popular in the country between 1950 and 1960. “Then a city like Berlin, for instance, I was thinking more of electronic music, Elektrowerk. A city like Moscow has kind of a heavy sound of a 19th-century Russian classical sort of thing, and those differences are really subtle from level to level.”

I was trying to create a very confined, restrained sound that was very light

The finer details that went into Mini Metro initially animated Vreeland and Dinosaur Polo Club to develop a separate soundtrack for the game, but working with a procedurally generated score made the reality of that more difficult than anticipated. One of the ideas they had while trying to find a workaround was an app that would run the game’s audio script. “It’s the weirdest thing,” Vreeland said in between laughs. “It’d be like taking the game and stripping [it] out and just leaving the audio.” Other potential solutions they tried included: a pile of assets and samples; recording the audio of a real playthrough in each level; releasing a different soundtrack for each level; and even seeding the soundtrack so each person would get a unique set of Mini Metro songs. “Those are hard to do, those still have the same sort of problems,” Vreeland said. “I find it very difficult to record the game and be like ‘here it is’. It just doesn’t feel right for whatever reason, so I haven’t been able to figure that out.”


Some months ago, Vreeland posted a two and a half minute song on his Soundcloud entitled “One Week,” which was an experiment he conducted to figure out what to do with Mini Metro‘s soundtrack. Thanks to his notes and the website’s graphical representation of the song, it is possible to notice a pattern between the soundwaves and single out each slope as a unique day of the week starting from Monday. The song starts slowly and calm, and increases throughout the week and along the hours of a single day. By the end of the week, between Friday and Saturday, the song loops until it fades out and finishes even slower than before, on Sunday. He explained that “this piece was like ‘Here’s the average work week for a commuter, someone who uses the subway system,’ where Monday is kind of starting slow and you’re tired, maybe from the weekend, and then your pace kind of picks up, and then by Friday it’s like ‘Woo, party!'” I first imagined the loop as a song at a party, like Daft Punk’s “One More Time”, but Vreeland explained it was also that “sound ringing in your head, and it’s like hammering a hangover. That was kind of the idea. And Sunday was really sleepy.”


The creative process behind Mini Metro demanded Vreeland to have a different working week than the average commuter his music was inspired by, though. He was a freelancer for Dinosaur Polo Club, working from home. And because Mini Metro was procedural and code-based, it influenced his process in a very different way than, say, writing music in a more traditional way. He didn’t only want to work well into the night, it was something of a necessity as he sorted through all of the game’s code, sifting it thoroughly with his eyes.

Even when he’s working on other projects, Vreeland notices different points in which his routine changes. “I’ve gone through phases where I’ll try to set a very rigid schedule for myself, where I’m saying ‘I’m gonna work on this project Monday, Tuesday, Wednesday from this time to this time’. And I found that… I mean, I guess some structures can be good, but I find life, in general, is very chaotic and I’m just trying to roll with it,” he told me. Vreeland is currently expecting another big shift in his routine for his next project with the Hyper Light Drifter team, for which he’s moving to Los Angeles for and will be commuting every day once he gets there.

he could allow himself to get burned out on one and then dip into the other as a break

He couldn’t give further information about this new project but he mentioned that his work on the soundtrack for Hyper Light Drifter, this year’s fantastic action role-playing game, was “very challenging emotionally,” at least when compared with his work on Mini Metro. “I think with Mini Metro I was trying to create a very confined, restrained sound that was very light,” he explained. He also considers Mini Metro more of an intellectual challenge while Hyper Light Drifter came in at the opposite end of the spectrum. It was very emotional to work on it. “When I’m thinking about writing for that, I’m thinking about ‘How can I make this as expressive as possible and just have a really sort of wide variety of sounds and textures to really play with the imagination?’”

As a result, Vreeland found that there were times when he would need a break from Hyper Light Drifter. “I needed to do something that was more laid back and where I could be more detached,” he said. The “emotional attachment” he developed with the fantasy RPG was due to his elevated expectations on his own work. “I saw this project as my primary project when I was working on it, everything else was secondary, so I put a lot of pressure on myself to reach a certain level.” Eventually, Vreeland gave up on some of his ideas, which is a telling contrast to the feature-creep design of Mini Metro. “I wanted the soundtrack of Hyper Light Drifter to be through composed, which means that the pieces would all be really long, like eight-minute pieces with lots and lots of sections, [but] it just didn’t work that way,” he said. “It was really hard to write that way because I was writing on the piano and then translating, and that was a nightmare.”

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Despite the occasional ache, Vreeland found the experience of working on Mini Metro and Hyper Light Drifter at the same time really valuable. While the workload came in doubles, it meant that he could allow himself to get burned out on one and then dip into the other as a break. But what he appreciates the most is that he can connect his work projects, all of them blending and washing into each other, the transition encouraging him to take new directions. It doesn’t matter if he’s writing for games, films, or any other medium, as long as he’s having a different experience during the creative process. “I just look at it more on a micro level, project to project, like ‘that project is gonna be different’,” he said. “I don’t want to always be doing crazy procedural audio systems. I wanna try different things.”