Colossal Order Ltd

Colossal Order

Game Development Studio

Welcome! It’s time for another Cities: Skylines II development diary. Today is all about game progression, which has two layers: Milestones and Development Trees. As you might expect, Milestones unlock new services, policies, and infoviews, but the process of unlocking them is different in Cities: Skylines II. Development Trees, an entirely new feature, exist for each service and bring a new level of customization to game progression. Both systems are tied together as Milestones give you points to spend in your Development Trees, allowing you to unlock more advanced services. 

Our goal with this approach was to give you the freedom to create the city you want without requiring you to reach high population numbers or using the Unlock All function. If you want to build just a small town next to the International Airport or the ChirpX Space Center, then you’re able to do just that. So, let’s dive into Milestones and Development Trees!


In Cities: Skylines, Milestones were unlocked by reaching certain population thresholds which varied depending on the buildable land of the map and gave you one path to the next Milestone: Build more residential areas. With Cities: Skylines II we have taken a different approach. Each Milestone is unlocked by reaching a specific amount of Expansion Points (XP), which are accumulated both passively and actively through building your city.

Passive Expansion Points are awarded 16 times throughout an in-game day as a result of increases in both Population and Happiness, giving a well-functioning city steady progress towards the next Milestone. Meanwhile, active Expansion Points are granted immediately as a result of actions you take, such as placing or upgrading a service building, constructing a signature building, or expanding the city’s road network.

Each milestone comes with several rewards and new options for your city

There are 20 Milestones to unlock, from Tiny Village all the way to Megapolis, and each one grants you a mix of Monetary rewards, Development Points, and Expansion Permits, as well as access to new City Services, Policies, and Management Options. As your city grows you will need to answer more of your citizens’ needs by providing them with additional services, such as Public Transportation and Communication. You also gain access to Districts and can customize areas of the city using Policies. You can find more about those topics in the City Services development diary.

Milestones also unlock new zone types to help your village grow into a thriving city, as well as more ways to control your city’s economy through increased Loan limits, Taxation, and Service Fees. If you missed it, we covered these options in the previous development diary Economy & Production

The number of Monetary rewards, Development Points, and Expansion Permits increases with each Milestone, enabling you to respond to your city’s growing needs. We discussed Expansion Permits in Maps & Themes, which just leaves Development Points, so let’s get into how they work.

See the rewards you’ve earned when you reach a Milestone and go straight to the Progression Panel to spend your Development Points right away


When you unlock a new service through a Milestone, you only unlock its basic buildings and features along with its corresponding Development Tree, which can be found in the Progressions interface. Here you can spend your Development Points to unlock more options, including more advanced and unique service buildings. Points can be spent as soon as you receive them or saved for later if you are not sure what you want to expand next.

You may want to unlock the Wastewater Treatment Plant to avoid polluting your surface water sources as soon as possible, maybe you want access to Harbors to benefit from the map’s seaways, or perhaps you want to provide your citizens with more sources of leisure with Sports Parks. As you unlock all Milestones you receive enough Development Points to unlock everything, but you choose the order depending on what your city needs the most.

Each Development Tree is divided into different Tiers and has a varying number of Nodes to unlock. The first Tier includes the basic buildings and functions of the service and this Node is automatically unlocked when you gain access to the service. As an example, when you first unlock Public Transportation, you have access to both Buses and Taxis as well as things like Stops and the Line Tool. The subsequent Tiers offer more advanced options which cost more Development Points to unlock, but provide you with new options.

Some services, such as Public Transportation, have multiple Branches with different options, and while you need to purchase the previous Nodes on a branch to unlock the next one, you do not need to purchase everything in a Tier to move on. For example, you can gain access to the International Airport without needing to unlock Water, Tram, or Subway transportation – as long as you have enough Development Points to afford it.

Development trees allow you to unlock new and more advanced options

How you choose to spend your Development Points shapes your city. Unlocking more transportation options early on allows you to integrate them as your city grows, while advanced power plants can provide your citizens with cheap and reliable electricity. We’re excited to hear which options you prioritize and how that differs from city to city. Next week we focus on the citizens of your city with the Citizen Simulation and Lifepath.

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