[sdwr]

What does clean room mean in this context? They built it from the assets with the game as a reference , but didn't look at the engine source code?

[brynnbee]

It means they didn't reference any existing or decompiled code from the original client. None of it is directly infringing on any copyright, though it may be doing so indirectly since there have been plenty of lawsuits for tools that contain no copyrighted information can but can used to facilitate infringement (e.g. a tool that decompiles a game ROM)

[alpb]

How about the assets?