If you look at the screenshots below, then you can see just how well this clone has been made. Quite a lot of craft has gone into this - even the login screen looks perfect.
Obviously, Microsoft can do little in the sense of stopping piracy here, since this is not their code. Still, the company could take the other intellectual property route, namely the one of copying copyrighted imagery and GUI elements. Ars spoke to Microsoft, and the Redmond giant has no plans to do anything about Ylmf OS.
"We have not really evaluated the code here, but assuming that this is a Linux implementation, we agree that the existing laws against software piracy are unlikely to apply here," Microsoft told Ars Technica, "So we'd have to look to the protection offered under intellectual property law generally in the relevant jurisdictions. But it would be difficult to talk about the legal options in a general sense as each instance is unique, depending not only on the local IP laws in play (in this case in China) but also the technical implementation itself. We'd need to drill down into the specifics to understand better what Microsoft IP rights may be at stake here."
The company added that it currently has no plans to drill down: "While we can't comment on the future, we have no current litigation efforts in place about this."
For now, you can download and play with Ylmf OS, assuming you can read Chinese.