@beardalaxy @wildgoose
The correct way of calling it is not a port, but rather a complete game engine rewrite. These are nothing new. The one's I've messed around with are OpenMW, DaggerfallUnity, VCMI and fheroes2. Notice that 2 of these are for Bethesda games (which has been incredibly friendly towards fans), and 2 of them are for games who's original dev has long since gone (and are now owned by Ubisoft, that doesn't really know what to do with the franchise, but is actually more friendly than you'd imagine towards these fans).

Thing is, from a legal point of view, as long as you still need the original assets, they might not that different from the usual mod. And we've seen time and time again how unfriendly devs will stop at nothing to shut down a mod they don't like, and how successful they can be.

And Take-Two is already paving the way to killing engine rewrites:
https://www.eurogamer.net/articles/2021-10-02-gta-reverse-engineering-fan-projects-pulled-offline-for-a-second-time-after-yet-another-take-two-takedown

They don't even have to win in court if they can file lawsuit after lawsuit until you can no longer afford to defend your creation.

Oh, and even IF you recreate all the assets, you're still infringing on the game mechanics of the original title.

P.S. Actually, I take it back. Engine rewrites might be more similar to emulated servers for online games (like WoW). Let me know how legal those are...