In a surprise move Unity has published the engine and editor C# source code on GitHub under a reference-only licence.

The technology firm stressed it was not releasing Unity as open source and that the main engine will remain proprietary for the foreseeable future.

The C# reference source code has been release under read-only terms rather than for modification.

“C# source of everything that goes into UnityEngine and UnityEditor managed assemblies, for every single version going back to Unity 2017.1,” said Unity's Aras Pranckevičius

“Going forward, the repository will be updated shortly after every new release. By looking at each commit you can see what has changed between successive version.”

No pull requests

Pranckevičius added Unity is not taking pull requests against the reference source code. He noted that Unity did not have the organisational framework to handle these requests and that any requests were still against the licence terms.

One of the main motivations for the move was that developers had already been providing GitHub repositories with disassembled code, which is technically against Unity’s terms of service and not legal.

You can check out the reference source code repository here.