When SayGames announced its partnership with Korean developer NLABSOFT in November 2025, the two companies were already collaborating on two projects. One was the already-released 'Tiny Warriors Rush,' while the other, 'Zombie Fortress,' was still in the testing phase. By last December, both games had been successfully launched in the global market.

First unveiled in December 2025, 'Zombie Fortress' quickly built a user base, racking up over 10k reviews and an average rating of 4.3 stars.

With live services and further development ongoing, we take a look behind the scenes at the NLABSOFT development team, their creative process, and how their partnership with SayGames is supporting the game's continued growth.

Zombie Fortress
From Core Vision to Finished Game

For NLABSOFT, 'Zombie Fortress' began with a very clear idea of the feeling the game should convey. "What we are most proud of is that 'Zombie Fortress' perfectly realized the core idea of its initial prototype, 'Zombie Crusher'," says NLABSOFT CEO Joo Jae-hyun. "From the start, our goal was to create a game that could be played casually on mobile while maximizing the intense, satisfying thrill of wiping out hordes of zombies."

While the zombie theme itself was familiar to global users, the team wanted to go beyond the traditional tower defense experience. By centering gameplay on 'traps' rather than standard towers, they designed the core loop around smashing, grinding, and exploding waves of incoming zombies.

One of the most critical aspects of development was finding the right balance between 'intuitiveness' and 'depth.' The goal was to make the game intuitively understandable while ensuring that each session remained engaging as complexity increased. "We invested a lot of time in balancing simplicity and impact," Joo adds. "We are very satisfied with the current result."

The team also wanted 'Zombie Fortress' to carry emotional weight beyond its simple mechanics. "Inspired by 'The Last of Us,' we chose a young girl as the protagonist. By placing her in a ruined world, we wanted to add a subtle narrative layer to the game," Joo explains intuitively.

Turning Data into Product Development Discussions

During development, "Zombie Fortress' underwent numerous iterations, including two major pivots that fundamentally restructured the game. While initial prototype tests showed strong potential with positive retention and session lengths, they also revealed clear limitations regarding onboarding and the complexity of meta-content for a broad global audience. Joo recalls, "At the time, it was difficult to set a clear direction with only limited internal data.

According to Joo, the collaboration with their publisher played a key role in systematizing product-related decisions. "Working with SayGames allowed us to approach improvements in stages," he notes. "We gained access to more extensive data, and by holding regular data-driven discussions, we were able to validate hypotheses instead of relying on guesswork."

SayGames producer Danila Katalev highlights the shared mindset behind this process: "I was thrilled to find a partner who shared a data-driven approach. We value the opportunity to review every test, every release, and every product change together in detail."

In the early version, players earned gold at the end of each wave, which they used to buy towers, upgrade archers, and increase earnings per battle. While functional, this system created friction in the play flow and made the onboarding process heavier than intended.

The first pivot restructured the purchasing flow. The team moved towers to a bottom menu and allowed players to upgrade the probability of obtaining higher-quality tower options. While intuitiveness improved, it still relied heavily on resource management.

The second pivot completely simplified the game loop. Gold and the purchase menu were removed entirely. Instead, after each wave, players choose between a tower or a perk to strengthen their build. This reduced cognitive load, made progression much more intuitive, and ultimately helped strengthen key metrics.

These pivots were part of a deliberate process to find growth points within the core loop. Each iteration led to clear improvements in funnel performance, retention, and overall lifetime engagement. By refining onboarding and simplifying progression, the development team strengthened key metrics and gained confidence for the global launch.

As the project's overall quality improved, data analysis became a core tool for product decision-making. By February 2026, over 100 new analytical events had been implemented, significantly expanding the team's ability to observe, test, and refine the user journey at every stage.

Danila describes the process: "The game is supported by 116 base dashboards in our internal analytics system. In addition, we built 12 custom dashboards specifically for "Zombie Fortress' to better understand how users interact with the game. Our main goal was to provide as much data as possible to help design and validate hypotheses for product improvement.

Through extensive A/B testing covering core features, monetization models, and content balance, the team was able to test hypotheses quickly and pivot with confidence. Since the global launch, the fact that one of the level balance dashboards alone has been accessed over 1186 times illustrates the team's ongoing commitment to fine-tuning the player experience.

Danila emphasizes that data analysis only works when combined with a clear creative direction. "No matter how vast your knowledge base or advanced your analytical technology, you cannot succeed without a clear vision of what the game should be," he says. "From day one, it was clear that the NLABSOFT team had a precise understanding of the experience they wanted to deliver and the story they wanted to tell."

Joo adds, "SayGames provided objective feedback from a global market perspective while consistently respecting our creative vision."

The collaboration between the two companies went beyond sharing reports or dashboards. Joo highlights the publishing team's active, hands-on involvement: "The SayGames team, including management, played the game extensively and provided very practical feedback on design and balance. Thanks to them, we gained the confidence to pause, rethink, and redesign whenever necessary."

Danila shares similar sentiments: "The NLABSOFT team is more than just experts. Our product meetings often felt like a private fan club gathering that you could only join if you had invested thousands of hours in the tower defense genre."

Joo summarizes this dynamic partnership with a clear metaphor: "We built a sturdy ship and prepared a map to cross the Pacific toward a treasure island. SayGames helped us interpret that map correctly and served as our radar and lighthouse throughout the voyage."

Why Execution Speed is NLABSOFT's 'Superpower'

This iterative approach is closely aligned with how the NLABSOFT team works. Although the studio is small, it boasts a wealth of experience, with members who have been developing mobile games together since 2010. Years of working in sync have resulted in a tight-knit, highly reliable collaborative structure where teamwork happens naturally.

"Each team member is an expert in their field, yet also possesses the ability to handle diverse roles. Planners, artists, and developers participate from the early stages, making decisions based on 'problem-solving' rather than job titles," Joo explains.

This flexibility shapes the studio's creative process. Planners don't just think about system logic; they constantly consider how a specific scene will be read intuitively, even in a short marketing video. This mindset significantly influences how the entire team evaluates and develops ideas.

Rather than refining concepts in isolation, NLABSOFT focuses on rapid implementation and validation. Joo explains, "We prefer to visualize ideas early and make decisions based on actual user feedback. Holding onto a concept for too long without testing only slows down development speed."

One approach that exemplifies this philosophy is the studio's 'Art Camp' method. Similar to songwriting camps in the music industry, this is a workshop where internal and external concept artists gather to explore various visual themes in a short, intensive period.

The team sketches contrasting concepts—such as 'Cavemen vs. Dinosaurs,' 'Farmers vs. Plants,' or 'Humans vs. Zombies'—and conducts CPI (Cost Per Install) tests for each. "By verifying which worldviews and visuals resonate most with users, we determine the final art direction based on data rather than relying solely on intuition," Joo explains, emphasizing that "both 'Tiny Warriors Rush' and 'Zombie Fortress' were born through this process."

When asked about the strength that defines the team, Joo didn't point to any single area. "If I had to define our superpower, it wouldn't be individual skill. It is the 'execution speed' driven by teamwork—the ability to quickly turn an idea into a powerful prototype and refine it into a product ready for the market without losing focus," he says.

For NLABSOFT, 'Zombie Fortress' is not a final destination, but a project that continues to evolve through iteration, trust, and a fast-moving team culture. As live services continue and the project evolves, the experience gained through the collaboration with SayGames is becoming a solid foundation not only for the game's own development but for future projects they will create together.