What is this?
The C# portion of the Unity game engine and editor source code, published by Unity Technologies for developers to read. It is a reference copy of engine internals, not a product you install or run.
The C# portion of the Unity game engine and editor source code, published by Unity Technologies for developers to read. It is a reference copy of engine internals, not a product you install or run.Is this something I can build with, or just code to read?Just code to read. It is a reference-only source tree — there is nothing to build, install or ship; the value is seeing how the engine and editor actually work inside.
Just code to read. It is a reference-only source tree — there is nothing to build, install or ship; the value is seeing how the engine and editor actually work inside.How do I browse it, then?Clone the repository and open the C# solution at Projects/CSharp/UnityReferenceSource.sln in any C# IDE. The folder layout mirrors Unity's internal source tree, which makes it easy to navigate.
Clone the repository and open the C# solution at Projects/CSharp/UnityReferenceSource.sln in any C# IDE. The folder layout mirrors Unity's internal source tree, which makes it easy to navigate.If I spot a bug in the code, can I just submit a fix?No — pull requests are not accepted. Genuine bugs should be filed through the Unity Bug Reporter instead.
No — pull requests are not accepted. Genuine bugs should be filed through the Unity Bug Reporter instead.Am I allowed to copy code from it into my own project?No. The terms of use allow reference reading only and forbid modifying or redistributing the C# code in source or binary form; changing Unity's source requires a commercial source code license from Unity sales.
No. The terms of use allow reference reading only and forbid modifying or redistributing the C# code in source or binary form; changing Unity's source requires a commercial source code license from Unity sales.Is the whole engine written in C#?No — this repository covers only the C# part. Unity's native core is C++, which is not published here; full source access is a commercial matter handled by Unity sales.
No — this repository covers only the C# part. Unity's native core is C++, which is not published here; full source access is a commercial matter handled by Unity sales.Is everything in the repo Unity's own code?No. The repository also includes third-party code, which is subject to separate third-party notices.
No. The repository also includes third-party code, which is subject to separate third-party notices.Why publish the source at all if it can't be modified?So developers can study how the Unity engine and editor actually work. Usage is deliberately restricted to reference, with stricter terms than an open-source project.
So developers can study how the Unity engine and editor actually work. Usage is deliberately restricted to reference, with stricter terms than an open-source project.What are similar projects?sbox-public, nakama, unity-mcp, AssetStudio, ArcadeMaker, csharplang, MonoGame, REDox
sbox-public, nakama, unity-mcp, AssetStudio, ArcadeMaker, csharplang, MonoGame, REDoxWhich topics is it in?unity3d, unity, engine, runtime, game-engine, gamedev, game-development, dotnet, programming, c#, csharp, reference
unity3d, unity, engine, runtime, game-engine, gamedev, game-development, dotnet, programming, c#, csharp, reference