We try to provide a blank canvas for the players to start building their own cities,” says Colossal Order’s CEO Mariina Hallikainen. This is not her first time at the rodeo: Colossal Order was founded on the idea of making a “city builder” in the style of classics like SimCity, and the studio already has two city builders under its belt, in the form of Cities in Motion and its sequel. “We’re huge fans of the genre,” says Hallikainen. “The idea has always been very clear in our heads, and I believe achieved in the development of Cities: Skylines.”

Indeed, Skylines is its most ambitious attempt to date. There are virtually no restrictions on where players can place structures, and there are tools for every job—a litany of different brush sizes and types for every purpose. When zoning neighborhoods, for instance, you can either employ the fill tool to designate a large section as a zone type, or zoom in to paint a tiny residential square inside a larger industrial area.

What’s more, players can bring their own structures and objects into the gameworld. “We’ve made an asset editor and the players can import their own assets into the game, and we’re looking forward to seeing the different styles of buildings the community will create,” says Hallikainen. The concept is simple: Build your own city, and make it functional, optimized and beautiful. Or not—it's really up to you.

Of course, you’re not all alone in the big city: icons pop up over homes showing what they’re missing (read: water, power), and as you hit population milestones, more options open up. You’ll need it all for an effective metropolis—schools, fire departments, police departments, trains and hospitals, to name but a few. You can map out and name specific districts, set tax rates, and add specific policies (a non-smoking suburb, perhaps?). Suffice it to say, SimCity fans should be in for a treat.

The team is now 13 large at Colossal Order, which is the biggest it’s ever been—in fact, they were only nine until last October. To make ends meet, they outsource some art, along with the audio and music. “The biggest challenge was to create our dream game with very limited resources,” says Hallikainen. “As we couldn't make the game big, we had to figure out how to make it shine. We’re looking forward to working on Cities: Skylines in the future, as we have many ideas left.”

The team turned to Unity because of its previous success in developing Cities in Motion 2 with the platform. “Unity's flexibility provided us a robust and powerful framework/engine to build upon,” says Hallikainen. To get the most of its software, the team at Colossal Order switched over to Unity 5 at a late date in the beta phase—and has never looked back. “The changes to Unity 5 from 4.x are obviously bigger than they would be in a minor release, but Unity's API migration tools made this step a walk in the park,” says Hallikainen. “Unity's profiler has been one of the more useful tools, and we also very much appreciated the added 64bit editor support.”

For Colossal Order, the Unity Asset Store proved rather useful in speeding up the prototyping phase. “At the very beginning of the project, we evaluated different GUI solutions present at the time,” says programmer Damien Morello. “NGUI and Daikon Forge stood out; it was interesting to see how different people approached implementing a GUI in Unity, as it was one of the most lacking features at the time.”

Ultimately, the experience served, more than anything, as a tool for the team to learn what it wanted instead. “If the package doesn’t do precisely what we need, we’re likely better off implementing our own,” says Morello. “We decided to go for a more minimalist solution that we would be more hands-on with, so we made an in-house framework for this. It was the right choice, since it turns out Unity GUI shipped only a few months before the end of the project, and most of the GUI had been implemented for some time already. We’ve already started to look into the new Unity GUI, and we’re impressed how easy and flexible it is. We’re most looking forward to start using it in our projects—maybe only for the next game, but maybe even for Cities: Skylines with future patches.”

While inspiration comes from across the gaming spectrum—according to Hallikainen, everyone on the team has a subtly different tastes, even in terms of city-building games—she’s been personally totally hooked by the Android puzzle adventure title Best Fiends. As for what she’s learned about achieving a high quality game with a small team and limited resources? Hallikainen’s answer might as well be that of an architect, or perhaps a general contractor: “Quality over quantity,” she says. “We focus on the foundation, and try to manage expectations.”

Cities: Skylines is currently available for Windows, Mac and Linux.

Unity 5

Despite the fact that Colossal Order’s Cities: Skylines was brought to Unity 5 at a relatively late stage of development, the team is hooked on the new features the new release brings with it. “We’re excited about the new features in Unity 5, which help us to bring something new to the game—even after the release,” says programmer Damien Morello.

The Frame Debugger was something the developers were been looking forward for quite some time, for instance. “We had used PIX in the past to verify our rendering worked somewhat as expected; but while it did the job, the integration of the frame debugger in the Unity Editor allows unprecedented iteration time to identify (and fix) a problem with our rendering, built on top of Unity's rendering pipeline,” he says. (Morello cites the common example of when LOD batching performs unexpectedly.) “The new control provided over native plug-ins and additional assemblies also helped us to clean up our project structure, since it’s now possible to ‘tag’ their platform and architecture.”

For example, the ability to optimize game objects for skeletal mesh rigs has been a boon to development, and is currently getting much use. “In the future, we’re impatient to look into the new deferred renderer and the Global Illumination capabilities,” says Morello. He points that while the team would have loved to have integrated it already, but it came too close to the end of their development cycle. “We chose to stick to the light prepass, since it is doing a very good job already. Still, we’re quite confident using those in our project will take the graphics to the next step.”