How to Structure a Large Roblox Codebase

The Service and Controller Pattern

The most common architecture for large Roblox games splits logic into Services (server-side) and Controllers (client-side). A Service is a ModuleScript that manages one domain of your game: CombatService handles damage and hit detection, InventoryService manages items, ProgressionService tracks quests and achievements. Each Service exposes a public API that other Services and server Scripts can call. Controllers follow the same pattern on the client: InputController handles player input, UIController manages screen elements, CameraController handles camera behavior. This separation makes each piece of logic self-contained, testable, and replaceable without affecting the rest of the codebase.

Shared Modules and the Dependency Question

Code that both server and client need, like data schemas, constants, utility functions, and type definitions, belongs in ReplicatedStorage under a Shared folder. Never duplicate logic between server and client scripts. If both need a damage formula, put it in a shared module and require it from both sides. For dependencies between modules, avoid circular requires at all costs. If ModuleA requires ModuleB and ModuleB requires ModuleA, your architecture has a design flaw. The fix is usually to extract the shared logic into a third module that both depend on, or to use an event-based communication pattern where modules emit signals instead of calling each other directly.

Folder Structure and Naming Conventions

A clean folder structure communicates architecture at a glance. A proven layout organizes code into three top-level categories:

• ServerScriptService/Server — contains server Services and the bootstrap script that initializes them
• StarterPlayerScripts/Client — contains client Controllers and the bootstrap script that initializes them
• ReplicatedStorage/Shared — contains modules used by both server and client: data schemas, constants, utility libraries, types
• ServerStorage/Assets — contains server-only assets like NPC models, loot tables, and map chunks
• ReplicatedStorage/Assets — contains client-accessible assets like UI prefabs, particle effects, and shared models

Dependency Injection and Initialization Order

Hard-coding require paths creates tight coupling. If CombatService directly requires InventoryService by path, moving InventoryService breaks CombatService. A dependency injection approach solves this: a central bootstrap script requires all Services, initializes them in order, and passes references to each Service during its Init phase. Each Service declares what it depends on, and the bootstrap resolves those dependencies. This pattern also gives you explicit control over initialization order, which matters when ServiceA depends on ServiceB being fully initialized before it can start. Without this, you end up with race conditions where modules try to use each other before they are ready.

Rojo and External Tooling

For serious Roblox development, Rojo is a near-essential tool. It syncs your project between an external code editor like VS Code and Roblox Studio. This gives you access to proper version control with Git, multi-file search and replace, linting with tools like Selene, type checking with Luau LSP, and all the productivity features of a real code editor. A Rojo project file defines how your file system maps to the Roblox data model. Once set up, you edit .lua files on disk, and Rojo live-syncs changes into Studio. This workflow also makes collaboration dramatically easier since multiple developers can work on different modules and merge changes through Git pull requests rather than editing in Studio simultaneously.

When to Refactor and When to Ship

Perfect architecture is the enemy of shipped games. If your project is under 5,000 lines of code, heavy architectural patterns add overhead without much benefit. Start simple: a few ModuleScripts with clear responsibilities, a Shared folder for common code, and consistent naming. Refactor when you feel the pain, not before. If you find yourself constantly searching for where logic lives, if adding a feature requires changing five files, or if bugs in one system cascade into others, those are signals that your structure needs work. The goal is not to have the most elegant codebase. It is to have a codebase that lets you build features quickly and fix bugs without fear.