Devsisters Engineering Day: Looking Back at Game Servers

On September 25, 2025, the 3rd Devsisters Engineering Day was held on the theme of game servers. Devsisters shared server technology and problem-solving experience accumulated from operating live games such as Cookie Run: Kingdom and Cookie Run: Tower of Adventures with the outside world.

The presentations consisted of two sessions. In the first session, a Cookie Run: Kingdom server engineer looked back on how the Scala-based real-time game backend was implemented, introducing an approach to achieving clear code, performance, scalability, and maintainability together through functional programming.

The second session covered the Asset Bundle update problem in Unity. To solve the issue where download size grows even from minor edits when many bundled resources are grouped together, a binary patch was applied, and the team shared a case where this significantly reduced download volume during resource updates and also cut CDN costs.

A 50-minute panel talk followed the presentations. Practical questions were exchanged, such as incident response manuals and real experiences, how to learn server development, and the background behind programming language choices for each game, with server engineers from various industries participating for an in-depth conversation.

At the back of the venue, a customized recruiting booth was also operated. Based on pre-registered information, attendees could talk directly with server developers from projects they were interested in, consulting in detail about technical challenges, team culture, growth potential, and career paths.

In closing, it was noted that across the past 3 events, wide-ranging technical topics spanning Infra/SRE, data, and game servers had been discussed, with plans to exchange insights with an even more diverse range of job functions in 2026. On a personal note, the presenter also mentioned the experience of building this event's introduction page using Claude Code, which became an occasion to genuinely appreciate the meaning of web development elements like the hero section, word break, and footer.