Colossal Order Ltd

Colossal Order

Game Development Studio

Hi everyone! We are back with another development diary for Cities: Skylines II and today is all about the game balancing. We want to give you a peek behind the curtain as we discuss our guiding principles and challenges in balancing Cities: Skylines II. Striking the right balance is always a challenge, but reaching a good balance for the various features is an important part of how the game plays and feels, and we believe it is especially important in simulation games.

GENERAL PROCESS

From the start, the vision has been to create an accessible, yet deep game, that is enjoyable for both new and experienced players. As an example, we created Government Subsidies to ensure a smooth early game progression. This mechanic helps burgeoning cities to cover running costs while there are few sources of income in the city. Once the city has grown enough and become self-sufficient, the subsidies decrease and eventually cease entirely. This means that the gameplay is easy to get into, but keeps you learning new things.

Another guiding idea has been to emphasize realism in the game. How buildings function, service budgets, trade, and citizen consumption have all been designed to be closer to how they appear in the real world. As a rule of thumb in our balancing we have kept in mind a town of roughly 10k citizens and how we would expect the game to function in a town of that size. For example, in Cities: Skylines II many of the power plants require fuel. In addition to maintaining good road connections to the power plant so it receives fuel to keep functioning, you need to keep in mind that the fuel actually costs money which is added to the base upkeep of the power plant.

A game of this size requires appropriate tools to keep all the features and their values in check. A master sheet of all the building values has been built over the course of the development to track and adjust them as needed. With the master sheet, we can easily make changes to a large selection of assets as we can use our own in-house tool to sync the values from the master sheet to the project, or vice versa allowing us to bring data and new assets from the project to the master sheet. On top of the master sheet, we have a multitude of other sheets on various other balancing aspects.

GAME PROGRESSION

A completely new progression system was developed for Cities: Skylines II. Milestones are unlocked by earning Experience Points (XP) as opposed to the population-based progression in Cities: Skylines which made the cities very similar to each other (requiring large cities to reach the final milestones). With active and passive XP you can create different kinds of cities, big and small, and still be able to achieve all of your goals. Balancing the progression, i.e. XP rewards is an important part of adjusting the pace of the game.

The game is paced so you always have things to do. In the early game, the XP progression has been balanced to allow you to experiment with all the newly unlocked features before reaching the next milestone. This allows the game to be learned and absorbed in good-sized chunks that do not overwhelm you but instead push you gently forward.

Balancing the XP rewards for building the city, placing buildings, and constructing roads was a tricky challenge. The XP rewards should be meaningful enough but not rack up XP too quickly so that the milestones aren’t reached in too quick succession. As an example, the road building rewards XP for each segment and if the amount is high, the road building alone can quickly fulfill the required amount to unlock the next milestone.

Adjusting the passive XP rewards was a new type of challenge for Cities: Skylines II. The passive XP route to unlocking milestones is slower than actively expanding the city, but it also fits quite well with the idea of small towns progressing slower than large cities in real life. Earning passive XP still has to be rewarding, so it can be a viable option to consider and thus balancing the passive rewards was crucial to get right.

While there definitely are ways to cheese the XP gains through just building buildings, as some buildings give more XP per Construction Cost, we have deliberately allowed that to keep the XP values in some sensical and understandable format. In our mind, it comes down to how you choose to play the game.

XP requirements for milestones increase exponentially and set the pace of the game

BUILDING STATS

Another important aspect of the game that needed balancing was the building stats, which govern the entire functionality of buildings. City services have service-specific stats and each service type has required a separate balancing cycle to make them function as intended in different-sized cities. As city services are upgradable providing more meaningful choices in the long run, we had to not only balance the buildings’ base stats but also consider the effects of the upgrades themselves. This meant looking at for example how much the upgrades increase the capacities of the buildings, how potential new functionality affects the city, whether there are any overlapping effects, and what the building and upkeep costs are compared to building the same city service building multiple times.

Zoned buildings and signature buildings fall into different categories depending on their zone type. Each zone type has balancing values that govern the entire zone type automatically. These include multipliers such as the size of the building lot and the number of floors and apartments for residential buildings. For workplaces, the size of the building affects the number of jobs and things such as storage space and production speed/capacity.

Signature buildings follow the same stats as regular zoned buildings, but to give them more meaning they also have various different effects which benefit the city. Some of these effects can give a local boost and some can even have a city-wide effect. To balance the effects the unlocking requirements have been put so that it feels like a meaningful building to achieve.


EXAMPLE CASE: ELEMENTARY SCHOOL
The elementary school has a short service coverage range and a small capacity which controls how far the well-being bonus for families reaches, shown in the game as the green color on the road network when the education info view is open. Families with children receive a small boost to their well-being when live in the green area. The well-being bonus gives families a reason to relocate closer to elementary schools and this simulates the idea of families wanting to live close to schools in real life. The reason for the short service coverage range and the small capacity is that we wanted to simulate the idea of each district of the city having its own elementary schools.

The master sheet provides a quick overview of our education buildings and allows us to easily make changes and apply them to the game

ELECTRICITY PRODUCTION

The last example of balancing we will look at today is electricity. The electricity production in Cities: Skylines II has been one of the most interesting and multifaceted things to balance in the game. In addition to the basic values for city service building and upkeep cost, we have had to think about how the availability of fuel and its price affects the functionality of the power plant and its upkeep cost (yes, this time the fuel used to keep the power plant running is part of its running cost!). We have also had to consider the building’s electricity output and fuel storage capacity as well as its pollution footprint.

One of the prevailing questions has been how to balance power plants that differ from each other quite a lot. As an example, we have the wind turbine which produces entirely clean energy, doesn’t require fuel, has a very limited pollution footprint (only noise pollution which in this case refers to it being a bit of an eyesore if placed in someone’s backyard) and is relatively cheap to build. We also have the coal power plant which in turn uses a lot of fuel, takes up a lot of space, and causes a lot of ground and air pollution, but it also has a higher energy output and, unlike the wind turbine, employs many workers.

Balancing these power plants requires a mix of mathematics and gameplay ideas. How do we compare clean energy and fossil fuel-based energy? How do we emphasize the pros and cons of the different ways to produce energy in a way that each choice you make is in itself a valid choice? And in the end, we also want to keep it grounded in realism: Coal is a more stable and high energy source compared to wind energy but on the other hand, it is far more polluting.

Balancing different sources of energy provided an interesting challenge

In addition to those considerations, we also want to keep in mind the different states of the city’s progression. Some power plants suit the different-sized cities better than others. A wind farm is an excellent and relatively cheap way to start a city but it can hardly power a growing metropolis by itself. And with the different power plants we want to provide you with the options to choose where to go from there and what fits your city’s needs and budget at any given time.

As you can tell, we put a lot more thought into balancing electricity production than just comparing the size and output stats of each building. We hope this leaves you with a lot of interesting and viable choices when you decide how to power your city, and as always, we look forward to hearing your feedback once you start building your own cities. Tomorrow, we switch topics and take a look at the technical side of Companies & Billboards.

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