How Doors Studio Turned an Experiment into a Fast-Growing Global Hit: The Story of BagMaster Isekai

Katya Sabirova

Today, that approach is paying off. BagMaster Isekai launched globally in March 2026, and within just two months it had become one of the most promising titles in SayGames' portfolio. Between March and May, the game grew from $26,000 to $250,000 in monthly IAP revenue (according to AppMagic), while monthly downloads increased from 320,000 to more than 800,000.

But behind those numbers is a story of creative risk, constant iteration, and learning how to build a game for a global audience. It's proof that trusting your own vision can pay off.

A Studio Built Around Craftsmanship

For Binh Diep, founding Doors Studio was a long-term personal ambition: "It has always been my dream to build world-class games together with fellow Vietnamese developers. That was the main reason I decided to end my 10-year journey as a Game Designer in China and return to Vietnam."

The vision behind Doors Studio was straightforward: create games with strong craftsmanship, distinctive ideas, and global appeal. BagMaster Isekai became the studio's first major step toward that goal.

An Unusual Combination That Worked

At first glance, BagMaster Isekai doesn't fit neatly into a single genre.

The game combines inventory management and item merging inspired by backpack-builders, roguelike progression systems, turn-based combat, and a lighthearted isekai setting.

Players manage their inventory, merge equipment into stronger gear, fight waves of enemies, choose upgrades that shape their builds, and gradually progress through dungeons and new regions.

What makes the game stand out is how these systems interact with each other. Every inventory decision affects combat performance, while every combat reward creates new strategic possibilities.

According to Binh Diep, the team itself wasn't sure how far the concept could go. "In the beginning, I wasn't sure how big it could become or how the market would react", – says Binh Diep.

As development continued, uncertainty gradually gave way to confidence. Binh Diep remembers: "Instead of worrying about the unknown, we focused on solving the challenges in front of us."

Building the Game Through Constant Reinvention

One of the most surprising aspects of BagMaster's development is how much of the game was rebuilt along the way.

Rather than protecting early decisions, the team repeatedly challenged their own assumptions. "The game has evolved drastically since its earliest iterations. We continuously tore down and rebuilt systems whenever we felt they could be better", – Binh Diep explains. 

That process was far from comfortable for the team. "Going through those massive overhauls was incredibly stressful each time, but looking back, the game became visibly better after every major iteration", – adds Binh Diep.

The willingness to rethink major decisions helped the project gradually move from an interesting prototype to a product capable of succeeding in a highly competitive market.

The Reality of Global Launch

Launching globally introduced an entirely new set of challenges.

The team suddenly had to support players across different regions, device generations, and gameplay styles. "I was honestly a bit overwhelmed by the sheer diversity of player habits and the wide range of devices they use to play our game”, - smiles Binh Diep.

The result was a flood of new technical requirements. This meant dealing with far more bugs and a much higher demand for performance optimization than the team had initially anticipated.

What helped the team navigate that transition was adaptability. "Fortunately, I am blessed with a team of fast learners who never hesitate to embrace change when faced with adversity", – says Binh Diep.

Also, the surprise came from just how quickly players mastered the game, how hardcore the players can be — they progress through and grind the game much faster than the team ever expected.

Perhaps even more valuable was the quality of community feedback. "They've provided incredibly insightful thoughts regarding gameplay and game balancing — creative ideas that even our team hadn't thought of before", – says Binh Diep. That feedback loop has become an important source of product improvement.

Creativity First, Validation Second

Despite relying heavily on analytics and player feedback, Doors Studio maintains a strong belief in creative intuition. For Binh Diep, every new idea starts with instinct: "We always try to carve out a dedicated space to listen to our own instincts regarding new ideas and the core direction of the game."

But intuition is only the beginning: "Right after that, we rigorously validate those ideas using data, player feedback, and market analysis."

As BagMaster Isekai evolved, SayGames' analytics platform became an important part of that validation process. Beyond standard product dashboards, the team relied on custom analytics tailored specifically to the game's systems, giving them the flexibility to run as many A/B tests as needed and evaluate new features before rolling them out to all players.

For a game with multiple progression systems, every new mechanic carries risk. According to Binh Diep, extensive experimentation allowed the team to reduce that risk while gaining detailed insights into what was — and wasn't — working.

One area where testing proved particularly valuable was difficulty balancing. The team initially underestimated how differently a global audience would respond to progression and challenge: "We had very little experience with global players and how subjective difficulty really is. Every time we needed to adjust progression, we relied on A/B tests to find the right answer."

Rather than relying on assumptions, the team used analytics to understand how players progressed through the game and where balancing changes improved the overall experience.

For Doors Studio, creativity and analytics are complementary rather than competing forces. One generates ideas; the other helps identify which ideas truly make the game better. That balance between intuition and evidence has become one of the team's core development principles.

Growing Together With the Game

As BagMaster Isekai grew, so did the studio behind it.

What started as a small team of just four developers gradually evolved into a significantly larger organization. By the time the game reached its global launch, the team had grown to seven people. Today, in June 2026, Doors Studio consists of twelve team members — tripling in size since the project began.

For Binh, this growth is one of the clearest indicators that the studio is moving in the right direction: "I'd say we have all leveled up significantly, both in terms of professional expertise and our overall team scale. I feel very fortunate that BagMaster Isekai has proved compelling enough to attract the right talent and top-tier professionals to join our team."

The Role of Partnership

When asked about the collaboration with SayGames, Binh Diep points not to a single feature or business milestone, but to the ability to stay focused on product development: "Thanks to the crucial support from SayGames at pivotal moments, our team was able to fully dedicate our minds and energy to the product itself."

That support spans multiple disciplines. "We've been supported by a large, highly professional, and enthusiastic team that covers every critical area needed for a game's healthy growth."

From analytics and product management to QA, localization, store management, and user acquisition, the collaboration allowed Doors Studio to access top-of-the market expertise that would have been difficult to build independently.

The relationship is built on something even more fundamental – trust and transparency are the absolute foundation of any successful partnership. According to Binh Diep, trust enables honest conversations, even when opinions differ: "Only when there is genuine trust can both sides openly share their raw perspectives on the product — even when there are strong disagreements."

At SayGames, the goal is not to dictate solutions, but to help teams identify opportunities and make informed decisions. 

As Danila Katalev, Producer at SayGames, says: "So many people inside SayGames genuinely choose to play BagMaster Isekai in their free time, and we're constantly waiting for the next update. 

You can feel the hand of an experienced game designer behind everything in the game. The team understands how games are usually built, yet they aren't afraid to challenge conventions and present familiar mechanics in unexpected ways. What really stands out is their attention to detail. Every mechanic is carefully crafted, tested, and refined. They build the kinds of features they genuinely want to see as players themselves - and that's where the game's originality comes from."

Looking Ahead

The team sees LiveOps becoming increasingly important as the game matures, but their primary focus remains unchanged. "Adding new content and fresh gameplay elements will always remain our top priority for the game, simply because that's where the core fun lies," – says Binh.

And while BagMaster Isekai has already achieved impressive growth, Binh Diep remains grounded about the future: "Since this is the first title from our studio, our biggest hope is simply that the game performs well enough to allow us to keep building better games".

For a project that started as an experiment, that's already a remarkable outcome. And judging by the game's growth trajectory, the story of BagMaster Isekai is only just beginning.