OpenMW is different. It does not use any Morrowind code, names or assets. It is a clean room re-implementation of an engine. So if you have Morrowind, you can use OpenMW to play it. If you have another game that uses the same file format, you can use OpenMW to play that.

That said, I can kinda see the OpenMW team having legal problems. Like, the website has Silt Striders in the background. Changelogs mention Morrowind NPCs and items. The release videos are absolutely covered in Morrowind assets, but they're not made by the OpenMW team, but they are linked by the OpenMW team so ¯\_(ツ)_/¯. The name "OpenMW" doesn't directly use the Morrowind name, but it's obviously a reference. I dunno what of that would/wouldn't be covered by fair use. IANAL.

None of that is the engine itself, though. If they were given a cease & desist, would it just be enough to purge the website of any Morrowind references and rename the engine to Open3DE?

And there's a lot of ways to interpret an email that is literally just

Yeah, this sounds reasonable.

Like... Maybe everything is in the clear. idk. IANAL. The point I'm trying to make is that situations like these are rarely super simple and clear cut. Ambiguities often don't work in our favor, and we're often not even aware of those ambiguities and what their likely interpretation is without a solid understanding of the law.

Maybe I'm bullshitting though and /u/VideoGameAttorney will rek me. That'd be cool too.