GREEのモバイルゲーム運用 — リアルタイム対戦と決済の裏側

GREE Inc. was founded in 2004, initially starting as a PC-oriented social networking service. It later pivoted to a mobile-phone game platform, and is today a company whose core business is operating mobile games. This article gives an overview of the company's technical foundation and operational structure.

Around 2007, the company saw rapid growth via simple HTML games for so-called feature phones ("garake"). However, from 2010 onward, with the spread of smartphones, the legacy carrier-billing-dependent model stopped working, forcing a company-wide technical transition. Existing Flash Lite assets were abandoned in favor of a full migration to HTML5 and native apps.

In current flagship titles, synchronous battles where players operate simultaneously are a standard feature. HTTP polling cannot keep latency within an acceptable range, so a permanent-connection platform based on WebSocket was adopted. The server side is implemented in Go, designed so that a single machine handles tens of thousands of concurrent connections.

State synchronization during battles uses an authoritative-server approach. Operation inputs sent from clients are validated on the server, and only the results are distributed to all players. This fundamentally prevents cheating via client-side tampering.

In-app purchases via the App Store and Google Play look simple at first glance, but incidents such as "payment completed but item not delivered" or "the same purchase counted twice" tend to occur due to network disconnections or device crashes. At GREE, each purchase transaction is bound to a unique receipt ID, and idempotent processing is thoroughly enforced on the server side.

In Japan's mobile game industry, a paid-lottery-style element called "gacha" is widely common. In 2016, the industry body JOGA made probability disclosure mandatory as voluntary self-regulation, and with the 2022 revision of the Consumer Affairs Agency's Premium Labeling Act operational standards, it became de facto a legal obligation.

At GREE, the drop rate of each gacha is disclosed in detail both in-game and on the official website. As internal implementation, automated consistency tests run on every deploy to ensure that the drop tables edited by planning staff always match the public display.

A certain proportion of players use modified clients or memory-tampering tools. At GREE, server-side behavior log analysis is combined with device-side modified-OS detection (so-called root/jailbreak detection) and machine-learning-based behavior pattern classification, building a multi-layered defense.

Especially in real-time battles, this is used together with the server-authoritative approach, and operations that violate physical laws or time limits are not accepted. Suspicious accounts are sent to a human review queue, ensuring strict handling while avoiding false detections.

The company undertook aggressive overseas expansion around 2011, including the acquisition of OpenFeint, but due to cultural differences and the strength of local competitors, by around 2014 it had downsized or withdrawn from many overseas bases. In recent years, it has been re-attempting expansion by re-releasing specific titles for North America and Asia.

From 2021 onward, GREE has entered the blockchain-game domain in earnest. Unlike traditional server-managed items, items issued as NFTs belong to users' wallets and can be traded on secondary markets. The company is exploring its own blockchain platforms and interoperability with other companies' chains, while advancing integration with existing games.

GREE's current challenge is to balance the stable operation of long-running titles with expansion into new technology domains. While refining the basic elements of real-time battles, payment, and anti-cheat, new attempts in overseas markets and the blockchain domain are expected to continue.