What MasterMemory Solves—and What It Doesn't: A Practical Guide to Static Game Data in Unity

Introduction When you build games with Unity, you eventually run into the problem of managing static game data—often called master data in Japanese game development. At first, ScriptableObject may be more than enough. If your project has a few dozen items, a few dozen enemies, and only a small number of stage definitions, ScriptableObject is convenient because you can inspect and edit everything directly in the Unity Editor. As the project grows, however, the situation changes. You may end up with tables for items, characters, skills, quests, rewards, shops, gacha pools, stages, enemy placements, progression curves, and localization text. The data is no longer edited only by programmers. Planners and game designers may need to work with it in Excel or Google Sheets. At that point, the problem is no longer just choosing a file format. You need to think about questions such as: How do you load a large amount of data quickly? How do you write ID lookups and composite-key queries safely? Should CSV or JSON be parsed directly at runtime? Is it reasonable to create a large number of Dictionaries? How do you validate references between tables? How do you debug data after converting it to binary? How do you connect the source data edited by planners to the data loaded by Unity? For the runtime loading and lookup part of that problem, one strong option is Cysharp's MasterMemory . The official README describes MasterMemory as a “Source Generator based Embedded Typed Readonly In-Memory Document Database” for .NET and Unity. In practical terms, you define your schema as C# types, a Source Generator creates a typed read-only in-memory database API, and the application loads MessagePack binary data that can be queried through type-safe methods. The official README highlights performance compared with SQLite, low allocation during queries, a small database size, and generated database structures that are type-safe and IDE-friendly. Cygames Engineers' Blog also has useful articles