This came from u/AlfredicEnglishRules Fan Made Videogames post and I think it deserves more attention and a direct DL link. Some guy took the LttP assets and put them in a solid roguelike with procedurally-generated dungeon levels, randomized pickups, and permadeath. Admittedly not particularly original, but I'm not a huge roguelike fan and the Zelda nostalgia boost makes it charming and more playable for me. I've killed plenty of time just trying to make it to B5.
The original download is only available on the developer's discord, and ain't nobody got time for that, so here's a copy on catbox:
Stuff like this is why I rarely bother with modern big budget games. There's plenty of old games, indies, and fan games to last a lifetime.
Mods are completely different than a new, stand-alone product. Even if they're reusing assets from a ROM, the actual distributable "code" is (essentially) entirely new. It's legal to create something new to modify something, and it's legal to modify something that you already own, so neither of those are legally actionable. Best they could do is send scary sounding letters making unenforceable demands.
And yeah, not everything gets struck down. Nintendo's Eye of Sauron legal team can't see everywhere at all times. But if you don't want to be spotted, at least don't try to wear the damn ring when you're in Mordor.
The OoT ones I am talking about are entirely stand alone products, using the assets and base of it to create what is basically an asset flip new game. I brought them up because I was just yesterday looking at something that is OoT but nearly exactly what OP is describing there. Perhaps "mods" was the wrong word of me to use, because I am not a tech code guy.
Point being, its a huge massive group of people making dozens of these by the month and they have been nearly uninterrupted for probably 15+ years. They aren't even quiet about it most of the time, as the LttP/Super Metroid crossover game was mainstream famous a few years ago.
Fair enough; as long as things remain niche, they'll probably be able to fly under the radar.
Anything that achieves widespread recognition will bring the fury of IP lawyers upon them.
And it will have been 100% avoidable. Don't use copyrighted artwork, and don't use trademarked names. That's all they have to do.