Cities: Skylines is a city-building game released in 2015. It was created by Colossal Order and published by Paradox Interactive. The game allows players to build and manage a city on their own. Players control how areas are zoned, where roads are placed, how taxes are set, and how public services and transportation systems are organized. They also manage the city’s budget, health, jobs, traffic, and pollution. Players can use a sandbox mode, which lets them build without strict rules, giving them more creative freedom.

Cities: Skylines is an improvement over Colossal Order’s earlier games, called Cities in Motion, which focused on designing transportation systems. Colossal Order believed they had the skills to expand their city-building game into a more detailed simulation. However, Paradox Interactive was hesitant at first because of the popularity of the SimCity series. After the 2013 SimCity game received poor reviews, Paradox saw an opportunity to create a competing game. Colossal Order aimed to build a game engine that could simulate the daily lives of nearly one million citizens while keeping the game easy to understand. This includes realistic traffic patterns and how traffic affects city services and areas. Since its release, the game has received many expansions and downloadable content (DLC). It also supports user-created content.

The game was first released for Windows, macOS, and Linux on March 10, 2015. Later versions were released for Xbox One and PlayStation 4 in 2017, Nintendo Switch in September 2018, and Google Stadia in May 2022. A remastered version for PlayStation 5 and Xbox Series X/S was released in February 2023. Critics praised the game, and it became a commercial success, selling over twelve million copies across all platforms by June 2022.

A sequel, Cities: Skylines II, was released on October 24, 2023, and received mixed reviews. The original game continued to receive updates after its release.

Gameplay

The player begins with a plot of land that is the same size as a 2-by-2-kilometre (1.2 mi × 1.2 mi) area. This includes access to a highway exit, a nearby body of water, and a starting amount of in-game money. The player builds roads and creates residential, industrial, and commercial zones. They also add basic services like power, water, and sewage to attract residents and provide jobs.

As the city grows and reaches certain population levels, the player unlocks new city improvements, such as schools, fire stations, police stations, healthcare facilities, waste management systems, tax policies, mass transit systems, and other tools for managing the city. One tool allows the player to divide parts of the city into districts. Each district can be set up to limit the types of buildings allowed, enforce specific rules, or adjust taxes for different areas. For example, a district might only allow agricultural industries, offer free public transportation, or discourage fossil-fuel vehicles while encouraging electric vehicles with the Green Cities DLC.

Buildings in the city have different development levels that improve when the local area is upgraded. Higher levels provide more benefits. For example, a commercial store may reach a higher level if nearby residents are more educated, which allows it to hire more workers and increase tax revenue. When the player has enough residents and money, they can buy nearby land plots, each the same size as the starting area. This allows them to build eight additional areas out of 25 total within a 10-by-10-kilometre (6.2 mi × 6.2 mi) area. The limit on parcels helps the game run smoothly on most computers, but players can use Steam Workshop modifications to expand the game’s map to include all 25 standard tiles or even the full map (81 tiles, covering 324 square kilometres or 125 square miles).

The game includes a detailed transportation system inspired by Colossal Order’s earlier game, Cities in Motion. Players can plan public transportation to reduce traffic and generate revenue. Roads can be built straight or in any shape, and the zoning grid adjusts to fit the road layout. Cities do not need to follow a square grid plan. Roads of different widths, including major highways, can handle varying traffic levels. Special road types, such as tree-lined avenues or highways with sound barriers, reduce noise or increase property values but cost more to build. Public transportation options like buses, taxis, trams, trains, ferries, and metro systems can be added to the road system.

Players can use the Steam Workshop to add custom content, such as new buildings or vehicles. Creating a community of players who share content was a key goal in the game’s design. The game includes pre-made terrains for building and a map editor that lets players create their own maps, including real-world geographic features. Some modifications can change core gameplay, such as bypassing population tier requirements, giving unlimited funds, or increasing difficulty.

Development

Finnish game developer Colossal Order, a small studio with thirteen members when Cities: Skylines was created, had previously gained recognition for its Cities in Motion series. This series focused on building transportation systems in pre-designed cities. Colossal Order aimed to create a larger city simulation game, similar to the SimCity franchise. To prepare, they developed Cities in Motion 2 using the Unity game engine to test their ability to create such a complex project. They shared their ideas with their publisher, Paradox Interactive, but the initial plans focused on managing a city politically, such as setting rules and regulations as a mayor. Paradox believed these ideas were not strong enough to compete with the well-known SimCity series and asked Colossal Order to revise their approach.

The situation changed when the 2013 version of SimCity was released and received poor reviews due to several problems. After discussing the city simulation idea with Colossal Order, Paradox saw an opportunity in the market and approved the development of Cities: Skylines.

One goal of the game was to simulate a city with up to one million residents. To achieve this, the developers created a system that showed how simulated citizens moved through roads and public transit. They found that a city’s success depended heavily on how well its roads were designed. Colossal Order had already understood the importance of road systems from their earlier work on Cities in Motion and believed that showing traffic and congestion visually helped players understand larger city design issues.

To represent traffic, Colossal Order built a complex system that calculated the fastest route for a simulated person traveling to work or other destinations, considering nearby roads and public transit. If a route changed during travel, the person would be instantly returned to their starting point instead of recalculating a new path. If the journey required driving, seven rules guided the simulated person’s behavior in traffic. Some rules were skipped in areas where the player was not looking to prevent traffic problems from spreading if the player changed the road system in real time. The game used a system that connected different points in the city to determine the fastest routes and identify intersections. This system simulated how individuals moved on roads and transit, considering other traffic and basic physics, such as vehicle speed on slopes and slowing down on sharp curves. The developers found that their model accurately showed how different types of road intersections, like single-point urban interchanges or diverging diamond interchanges, affected traffic efficiency.

Release

Cities: Skylines was announced by publisher Paradox Interactive on August 14, 2014, at Gamescom. The announcement trailer highlighted that players could "build [their] dream city," "mod and share online," and "play offline." Journalists noted that the ability to play without an internet connection was seen as a response to SimCity, which initially required an internet connection during gameplay. The game uses an adapted Unity engine and officially supports player-created modifications. It was released on March 10, 2015, with Colossal Order committed to supporting it after release. Tantalus Media helped Paradox port the game to Xbox One and Windows 10, which was released on April 21, 2017. This version included the After Dark expansion and supported all downloadable content. Tantalus also ported the game and After Dark expansion for PlayStation 4, released on August 15, 2017. Physical copies of the Xbox One and PlayStation 4 versions were distributed by Koch Media. Tantalus later ported the game and After Dark expansion for Nintendo Switch, released on September 13, 2018, which included the "After Dark" and "Snowfall" expansions.

The game was designed from the start to support player-created modifications, connecting with Steam Workshop. Colossal Order observed that with Cities in Motion, players quickly modified and expanded the game. They wanted to encourage similar creativity in Cities: Skylines, recognizing that modding was important to players and would not reduce the game's value. Within a month of release, over 20,000 assets were created in the Workshop, including modifications that added first-person mode and a flying simulator. By February 2020, over 200,000 user-created items were available. Many fans used crowdfunding platforms like Patreon to fund their work. Paradox began working with modders to create official content packs starting in 2016. The first was a set of art deco-inspired buildings created by Matt Crux, who received a share of the sales from Paradox.

An educational version of Cities: Skylines was developed by Colossal Order with TeacherGaming and released in May 2018. This version includes classroom tutorials, scenarios, and tools for teachers to track student progress.

A remastered version of Cities: Skylines was released exclusively for PlayStation 5 and Xbox Series X/S on February 15, 2023. It features a larger building area, performance improvements, and quality-of-life updates. Players who owned the PlayStation 4 or Xbox One versions received the upgrade for free.

A virtual reality version of the game, titled Cities: VR, developed by Fast Travel Games, was released for Meta Quest 2 on April 28, 2022, and later for PlayStation VR2.

Reception

Upon its release, Cities: Skylines received mostly good reviews from critics, according to Metacritic. IGN gave the game a score of 8.5 and noted that while the game does not include exciting scenarios or random events, it impresses with its large scale and many features. Destructoid awarded the game a 9 out of 10, stating that Cities: Skylines returns to the ideas that made city-building games popular and expands them. The reviewer enjoyed playing the game and said it encouraged creativity and imagination. The Escapist gave the game a perfect score, highlighting its low price and stating it is the best city-building game in over 10 years, despite a few small flaws.

Many critics compared Cities: Skylines to SimCity, which was considered the top game in the genre by some, including the CEO of Colossal Order. When Cities: Skylines was first announced, journalists saw it as a competitor to the 2013 SimCity reboot, which had received poor reviews. Some described Cities: Skylines as a solution to the problems of the SimCity reboot and a game that met needs SimCity could not. A Eurogamer article discussed the difference in size between Colossal Order (then a nine-person team) and Maxis, the company behind SimCity. Most critics believed Cities: Skylines became better than SimCity in all areas, according to The Escapist. However, some critics noted that the game lacked disasters and random events, which SimCity included, as well as a detailed tutorial. These features were later added through a DLC called Natural Disasters.

The city government of Stockholm, where Paradox Interactive (the company behind Cities: Skylines) is based, used the game to plan a new transportation system. The developer of Bus Simulator 18 used Cities: Skylines to design the roads and highways in their game’s world map, creating a realistic city layout. A Polish YouTuber used the game to recreate a planned highway interchange near Kraków, showing how it caused traffic jams and complicated lane changes. After reviewing the issue, the Polish General Directorate for National Roads and Highways ordered further analysis, which confirmed the problems, leading to a redesign of the interchange.

In 2020, Rock, Paper, Shotgun ranked Cities: Skylines as the fourth best management game on PC. At the 19th Annual D.I.C.E. Awards, the Academy of Interactive Arts & Sciences nominated Cities: Skylines for "Strategy/Simulation Game of the Year."

Cities: Skylines is Paradox Interactive’s best-selling game. Within 24 hours of its release, 250,000 copies were sold. Within a week, 500,000 copies were sold. Within a month, one million copies were sold. On its first anniversary, the game reached two million copies sold. By its second anniversary, sales reached 3.5 million copies. In March 2018, it was reported that the game had sold over five million copies on PC alone. On its fourth anniversary in March 2019, Colossal Order announced that Cities: Skylines had sold six million copies across all platforms. In June 2022, it was announced that the game had sold 12 million copies on all platforms. It is the best-selling game developed in Finland.

Researchers have studied the use of Cities: Skylines as a teaching tool for subjects such as real estate, environmental science, urban planning, and journalism. The game’s marketing also promoted its use as an educational tool through a video series called "city builders," which also supported an educational series by Justin Roczniak that uses Cities: Skylines as a visual aid.

Downloadable content

Since its release in 2015, the game Cities: Skylines has been given many types of extra content that players can download. These include expansion packs, cosmetic packs, content creator packs, flavor packs, music packs, and map packs. At first, this extra content was made available for the PC version of the game before being released on consoles a few months later. However, newer downloadable content has been released at the same time for both PC and consoles.

Sequel

Paradox Interactive said they would make a new game called Cities: Skylines II in March 2023. The game came out for Windows on October 24, 2023. Plans for the Xbox Series X/S and PlayStation 5 versions were first set for the second quarter of 2024, then delayed until October 2024. Later, the release for those systems was put off without a new date.