Cities: Skylines has sold 2 million units

Exactly a year after its initial release, Cities: Skylines has sold 2 million copies worldwide across Windows, Mac and Linux PCs.

That Colossal Order's city-builder would be successful was apparent from the outset. The game broke the 24-hour sales record for its publisher, Paradox Interactive, and went on to sell 1 million units in its first month.

"We knew that trying to create a city-building game with such a small team was an ambitious project, but we'd been working towards that goal ever since the first Cities in Motion title, and we knew, if given the chance, that we could make it happen," said Colossal Order CEO Mariina Hallikainen in a statement. "A year ago, we achieved that goal, and the results have been nothing short of incredible.

Fredrik Wester, CEO of Paradox Interactive, said that the game's modding community has been essential, allowing Cities: Skylines to keep, "growing and changing," even a year after launch. According to Wester, there are more than 76,000 pieces of mod content available through Steam Workshop.

And that's no accident. Speaking to GamesIndustry.biz last year, Mariina Hallikainen said that the team saw supporting the modding community as a desirable alternative to simply buying interest through post-launch marketing. Despite having a core team of a dozen or so people, Colossal Order committed one of its engineers to creating those tools for an entire year.