A monorepo is a single version control repository containing multiple projects or components. The concept has gained popularity in software engineering because it simplifies dependency management, makes cross-project changes atomic, and gives you a unified history for your whole codebase.
For game development, the case for a monorepo is intuitive. Your game engine, your game code, your build tools, and your content pipeline all need to work together. Keeping them in one repo means a single commit can update the engine and the game simultaneously, with no version mismatch. It means your CI system runs against the actual state of everything, not a snapshot of each piece independently.
The problems show up when you actually try it with game-scale repos.
Why Game Monorepos Are Hard
Size
A software monorepo at a large company might be several hundred megabytes of code. A game monorepo at a mid-size studio includes the engine source, all game code, and all assets — which can be 50GB, 100GB, or more. Standard monorepo tooling was not designed for this.
Sparse checkout — checking out only the subset of the repo you need — becomes essential. Without it, every engineer clones 100GB to work on a 50KB file. Git and Perforce both support sparse checkout, but neither makes it easy to configure for large teams without infrastructure work.
Engine source builds
If you are including the engine source in your monorepo (common when using Unreal Engine 4 or 5 from source), every clean build compiles the engine. That can be 1-2 hours. Your CI system needs precompiled engine binaries cached and only recompiles when the engine source actually changes. This requires careful build dependency tracking and a cache invalidation strategy that is more complex than standard CI setups.
Tooling assumptions
Most monorepo tools — Bazel, Nx, Turborepo, Pants — assume code projects with fast build times and unit tests. They model build graphs in terms of compilable code. They do not model asset import pipelines, shader compilation, or platform packaging. Adapting these tools to game development requires significant custom configuration and often custom build rule implementations.
What Actually Works
Separate the asset library
Keep source assets — raw textures, audio files, DCC source files — in a separate repository or at minimum a separate subtree of the monorepo. Use sparse checkout so that engineers and programmers who do not need assets never download them. Artists who do not need engine source never clone it.
The monorepo for code and engine can be lean. The asset repository can be large but only checked out by those who need it.
Use shallow clones for CI
Your CI system does not need full history. A shallow clone with depth 1 downloads the current state of the branch without any historical commits. For a monorepo with thousands of commits and large history, this difference is significant — full clone might take 30 minutes, shallow clone might take 2 minutes.
Pin engine binaries, not engine source
For most studios, only a few people ever modify the engine itself. Consider keeping the engine source in a separate repository and treating compiled engine binaries as a build artifact that is pinned by version in the main monorepo. When the engine team updates the engine, they tag a version. Game code consumes that tag. This is similar to how dependency management works for code libraries.
This approach gives you atomic version pinning (you know exactly which engine version every commit was built against) without forcing every developer to clone and understand the full engine source.
Lazy fetching for content
For the assets that do need to be in the same repository as the code, lazy fetching is essential. Engineers working on game systems should be able to sync only the assets needed for their current task. A character programmer does not need to download all the environment art. A UI engineer does not need the full audio bank.
This requires your version control system to support partial checkout with on-demand download of assets, and it requires your build system to know what assets each task requires.
Is a Monorepo Right for Your Studio?
It depends on how often you need cross-cutting changes that affect both engine and game simultaneously. If your engine team and game team work mostly independently, separate repos with versioned engine artifacts might be simpler to manage. If you make frequent changes that span both — engine feature + game usage in one commit — a monorepo reduces coordination overhead.
For studios at early stages, a monorepo with careful sparse checkout configuration is usually manageable. For larger studios with dedicated engine teams, the separation model often makes more sense operationally. The right answer is specific to how your team works, not a general principle.
The universal requirement, regardless of monorepo or multi-repo, is that your version control system handles game-scale binary assets efficiently. That constraint shapes every other decision in the architecture.