Rome’s traffic systems and waste works weren’t built in a day. The construction of Cities: Skylines began six years ago in populous Tampere, the city between two seemingly terraformed lakes in southern Finland. There, five developers founded Colossal Order with the intention of one day making a city builder.
“We had the dream,” said CEO Mariina Hallikainen, “But with the small team we had back in 2009 we were scared to go and attempt such a big game.”
Just as great cities are made from hamlets that grow and merge so closely that the seams disappear, Skylines’ constituent parts have been a long time in the making.
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Colossal Order took one element of the classic city builder - mass transit - and made it the focus of their first game, Cities in Motion.
Like Transport Tycoon, Cities in Motion positioned players not as gods or mayors but lowly transport chiefs - responsible for improving the public networks in Amsterdam, Berlin, Helsinki and Vienna. It was, says Hallikainen, “where it all began”. But a big chunk of it also had to be left behind.
Cities in Motion was built on tech that one of Colossal’s original team had been working on and maintaining for six years before starting the company. And it would have to be scrapped. Colossal had no choice: they planned to make “bigger and better games”.
“It was completely impossible to sustain our in-house technology without huge resources,” said Hallikainen, “which we didn’t have.”
And so Cities in Motion 2 was made in Unity, by a team of seven. It incorporated new features at the behest of Colossal’s budding community: day/night cycles; rush hour; custom timetables. Remarkably, it took just a year and a half to build.
There’s an internal wiki page where Colossal Order staff pitch in on the design process. After work concluded on Cities in Motion 2, that wiki filled up with new game ideas. One, from Mariina, was a stable manager sim (“I love horses - I think that would be huge in Germany”). Another was the city builder they’d dreamt of.
It wasn’t the first time they’d pitched Skylines, or something like it, to their longtime publisher Paradox. But it was the first time they’d done so in the aftermath of Maxis’ SimCity reboot. EA had succeeded in reviving appetite for the simulation genre, but not quite managed to capitalise on it.
“Finally,” said Hallikainen, “they went with it.”
Colossal Order knew what they wanted. A deep simulation with individually modelled entities: citizens with their own names, ages and workplaces.
“It creates realistic traffic, it creates realistic flows,” explained Hallikainen. “The [citizens] are born there and eventually they die.”
They knew they wanted it to be beautiful - something they hadn’t always been able to prioritise, but were sure they could pull off by sticking religiously to their own artistic guidelines. And they knew they wanted big maps.
“A sandbox,” said Hallikainen. “Just to make it so you had the room to make your own cities.”
The last point was particularly tricky. There’s always a trade-off in development between performance and memory - presumably the same Maxis wrestled with and eventually compromised on. Colossal Order had to get “really creative” to make their maps happen - in one instance coding on top of Unity to get dynamic water working.
It’s important to note that even now, the studio aren’t exactly overstaffed with coders. The Skylines team numbered nine, including management in the form of Mariina. It had just one designer, a handful of artists, and a pair of programmers.
“We basically doubled the programming resource by having two,” said Hallikainen.
Colossal Order’s designers don’t necessarily have coding experience, either. That’s something they like - it means they’re “not limited by the technical aspects of making games”, and can think outside those constraints. It’s then the job of those two programmers to work out how to make the designs work.
“I think this is very important, because it pushes the limits we have,” said Hallikainen. “It is something you can see in Cities: Skylines.”
There’s another reason Skylines turned out as well as it did. Colossal Order do their best to nail their designs in prototype, to make sure they’re fun and working - and work extra space into the schedule to ensure there’s time for a few reworks.
“When entering production, there’s not so much room for prototyping and it’s not so easy to implement new ideas,” said Hallikainen. “When somebody has a good idea, we really want to take advantage of that.”
Only one idea didn’t work out so well - one of Mariina’s. During development, the team ummed and ahhed over how to give players feedback on the effects of their actions. They considered an in-game newspaper - but Hallikainen, walking by, decided that wasn’t nearly modern enough.
“This has been one of the more controversial features, in the sense that before we released the game people seemed to really hate the blue bird,” laughed Hallikainen. “I’m pretty sure the team doesn’t want to hear my opinions ever again.”
We know what happened next. Cities: Skylines released March 10th and sold 250,000 copies in its first 24 hours, breaking Paradox’s records. It’s now shifted over a million.
“It pretty much blew us away,” said Hallikainen. “We knew we had a good game in our hands, but to have people embrace it so quickly... It really just went better than we ever expected.”
Twitch had a huge amount to do with it. Paradox released copies of the game to streamers two weeks early, and Cities peaked as the second most-watched game on the service.
“That was huge,” said Hallikainen. “I think that was a genius move from the Paradox marketing team.”