Hello all, it's Cassel, developer of <Ratopia>.

It's hard to believe that next week will mark a full year since we launched Early Access. Initially, we anticipated that about a year would be sufficient to refine the game’s quality, but we haven’t yet reached the level of content and polish we aimed for, so it seems we'll need to extend the Early Access period through the first half of next year.

We’re now developing with the official release timeline in mind, and as the year-end approaches, each day feels busier and more intense. Despite reducing our participation in exhibitions to stay focused on development, our ambition to expand content has kept us feeling short on time.

In this DevDiary, we initially hoped to share the finalized plans for the Spell and Religion in detail, but the planning expanded, requiring additional technical review time, so not as much progress was made. Therefore, this time, we'll provide a brief overview of the background and outline for the Spell and Religion and introduce the new Disease system, scheduled for an update next week.




The Shaman theme, along with the Navigator theme, was part of <Ratopia>’s core concept from the early stages of development. The central idea of the Shaman theme was to increase city efficiency by utilizing the deaths of Ratizens and enemies. However, adding such a large-scale system within our limited development time was a high-risk and unrealistic goal, much like the Electricity in game. We felt it would be more practical to introduce it as a DLC if the game sold well after the official release, allowing us to dedicate time to it. As a result, the Shaman theme remained as a plan tucked away in the depths of our memory for a long time.


If only there were a spell to increase development efficiency...!Then, while discussing enemy defeat rewards, as mentioned in the last Development Diary, it dawned on us that we could enhance the reward system by incorporating the Shaman theme. Expanding the enemy defeat rewards would naturally and efficiently tie into the Shaman theme, so I tried casting a “spell” to prioritize the Shaman theme’s development. However, it didn’t quite work as planned. Given that the Shaman theme is intended as content-rich and substantial, adding it in a small portion might not be satisfying, and it seemed risky to allocate extensive development time to the Shaman theme solely for the sake of enemy defeat rewards.

In the end, we decided to separate the enemy defeat rewards from the Shaman theme. Nevertheless, bringing the Shaman theme out from the back of our minds and into active development has allowed us to start shaping its framework. Through numerous discussions and brainstorming sessions, we’ve managed to gather a variety of fresh ideas.


An Idea for a Spell that Imposes a Lifespan Limit

In the past, we gathered user feedback and drafted a document outlining a system for Ratizens' aging, parenting, reproduction, and eventual death. However, we struggled with finding a way to manage the hassle that would come from handling the aging and deaths of over a hundred Ratizens. Given the game structure where each Ratizen needs a designated workplace, we were concerned that having to continually reassign each Ratizen could be quite inconvenient for the player.


A baby rat can’t work, and an elderly rat’s efficiency declines if they do.But what if we used magic? If a spell could temporarily boost the efficiency of certain Ratizens while gradually increasing their chance of death with each use, it might help reduce player resistance. This way, players could choose to balance Ratizen efficiency with the risk of death, allowing them to control the difficulty and inconvenience of managing Ratizens.

This type of spell would be designed to use the souls of deceased Ratizens or enemies. Additionally, dividing Ratizens into groups who support or oppose this soul-harnessing method could create a choice for the player, letting them decide how to collect souls and how extensively to use these spells.


Focusing on Religion Rather Than Spell

On the other hand, some felt it might be risky to emphasize elements like souls or Spell. Although <Ratropolis> featured Spell and Souls, these elements might not fit as well in <Ratopia>, which emphasizes a bit more realistic styled economics and city management. Using magic to resolve realistic or economic issues in <Ratopia> could feel out of place.

So this time, we explored a concept closer to "Religion" rather than "Spell." Players can create their own religion, selecting one positive and one negative effect for their doctrines. Once shrines are built throughout the city, Ratizens who use them will experience the effects of the player’s chosen doctrine. As the number of followers grows, additional effects can be added to the doctrine. However, attracting more followers becomes increasingly challenging without careful city planning.


This is similar to the Ideology DLC in <RimWorld> or the religion creation system in <Crusader Kings III>.


By using this system, Ratizens would no longer feel dissatisfied about the lack of joy facilities in the city, allowing the player to pursue unique, concept-driven playstyles, like requiring only vegetarian diets. However, there weren’t many elements that directly influenced the deaths of Ratizens and enemies, and as freedom increased, there were limitations on the types of buildings or content that could be added beyond parameter adjustments.


An Idea for Balancing Between Two Religions

This time, we aimed to introduce a new mechanism not previously available to players, encouraging them to think about how to integrate it with existing systems.

In the game, two religions—Umbran and Purgon—emerge, each with a unique way to expand its followers. Umbran, a group that reveres magic and knowledge, uses the souls of deceased Ratizens and enemies to boost city efficiency. In contrast, Purgon is a martial faction that harnesses spirits, emphasizing city order through the sacrifice of Ratizens. Buildings with new functions are designed to become accessible when the number of followers in each religion reaches a certain threshold.


The cards and concepts from <Ratropolis> were instrumental in developing ideas for Umbran and Purgon.

Prototype of the religion tech tree. While it’s still fairly empty, we’re looking forward to the day it’s filled with about 30 research elements.Concept art for Umbran and Purgon buildings. We also transferred existing buildings into the Shaman theme to enhance thematic consistency.Through this, we aimed to allow players to experience new features as they spread their chosen religion, while also encouraging them to adopt aspects of the other religion’s functionality. The intention was for players to weigh the pros and cons of blending religions and to think carefully about how to utilize each. This would involve optimizing city efficiency through spatial management and Ratizen allocation.

This idea requires a significant amount of development work, making it the most resource-intensive feature, but we believe it could become extensive content that aligns well with the theme. While technical reviews are still ongoing, so it’s too early to confirm, we are designing it to incorporate various user-suggested ideas, such as communal beds and the ability to change Ratizen traits. If you have any fun ideas that might fit well with the Shaman theme, feel free to share them in the comments!




Diseases are negative conditions that arise when Ratizens remain in low hygiene conditions for extended periods or due to certain events. Although mentioned in game descriptions for a long time, it’s a feature that hasn’t yet been implemented.

Just as Ratizens die from starvation if food supply is withheld for too long, we wanted diseases to pose a similar threat, where neglect could lead to Ratizen fatalities. Given that the Shaman theme plans to include effects related to Ratizen deaths, we decided that implementing the disease system first would be timely.

The biggest differences between disease and starvation are the stages of the condition and the possibility of contagion. Diseases progress through initial, mid, and terminal stages. In the early stage, there isn’t much of an issue, but if hygiene isn’t maintained or treatment isn’t provided within a certain period, the disease progresses to the mid-stage. When a Ratizen reaches the mid-stage and uses a building, that building becomes contaminated, allowing other Ratizens who use it afterward to have a small chance of contracting the disease in its early stage. If a Ratizen in the terminal stage doesn’t receive treatment, they face a high risk of death, meaning that without swift treatment or isolation, the city’s situation could quickly worsen.

However, implementing the function for Ratizens to leave disease in buildings they visit posed challenges. Given the variety in building types and forms, adding a contagious state to each one would be quite labor-intensive. To address this, we looked to the existing Ratizen interaction system, modifying it so that infected Ratizens would transmit the disease to nearby Ratizens instead of engaging in conversation.


A disease that compels others to mimic actions…?


However, Ratizens in <Ratopia> were designed to only converse with nearby Ratizens when they had no other tasks to complete. Much like in our bustling modern society, Ratizens almost always have tasks queued up, meaning conversations are rare. This meant that if an infected Ratizen attempted to start a conversation with another Ratizen, a player could simply order them to dig a hole, effectively preventing the spread of disease—a rather ingenious prevention method.

Testing revealed that the anticipated sense of crisis from disease wasn’t quite there, highlighting the need for a more effective method to spread infection. During this time, we recalled the recently added snail AI, which leaves a trail of slime as it moves across the map. Inspired by this, we considered configuring the system so that an infected Ratizen would leave a secretion after performing certain actions, such as sleeping, eating, or engaging in leisure activities. Other Ratizens who come into contact with this secretion would have a certain probability of becoming infected.


Ratizens leaving germ-filled secretions…


An infected Ratizen can be fully protected from spreading disease by receiving treatment at the hospital or being supplied with necessities like soap. However, this approach felt a bit too straightforward and uniform. To address this, we wanted to introduce an immunity value that would determine the likelihood of contracting disease. As the city develops, more factors would be introduced to boost immunity, making disease prevention easier.

However, implementing and explaining new attributes like immunity proved challenging in terms of tutorials and UI, and with other development tasks piling up, attempting these changes immediately wasn’t feasible.


With the addition of diseases in the game, we also incorporated disease-related effects into existing events and added milestone effects to help players prevent or utilize diseases. We’re excited to see how players experience and make use of these features.

One concern, however, is that while we envisioned scenarios where a peaceful city could be thrown into crisis by disease, players who manage basic hygiene well may rarely encounter disease, raising questions about whether many players will experience it, or if it may be too harsh for beginners. We’ll need to keep monitoring and adjusting to see how much disease impacts cities. After the update next week, we would greatly appreciate your feedback if you get a chance to experience the disease system!


Let’s build enough toilets so the Ratizens can take care of their bathroom needs comfortably.While we couldn’t cover everything in this DevDiary, we’ve also been working on new Electricity Structures and a in-game Halloween event. These are scheduled to launch alongside the disease system next week, so please look forward to it! And if you know anyone who hasn’t purchased the game yet, a discount is planned starting on November 10, so we’d be grateful if you spread the word! As the weather gets colder, please stay safe from illness, and have a healthy month ahead!