@TerminalAutism @ryo A spiritual successor does not infringe on copyright.
@ryo @TerminalAutism @Alex A lot of ROM hacks uses patches which makes them somewhat less copyright infringing. At that point, it would be no different than a mod for a PC game.
Nintendo also doesn't seem to care about fan translations like the Mother 3 fan translation. I guess they feel like since it's unlikely that game will get a localization anytime soon that taking it down would be a dick move.
They have also turned a blind eye to anything related to the Satellaview, but that's probably because it is literally impossible to get those games anywhere else and what is left of many of those games are incomplete since a lot of them were meant to be played along with an audio broadcast (though for the BS Zelda games, the audio has been recently re-dubbed thanks to a custom SNES chip, the MSU-1 which allows MP3 quality audio on the SNES).
And recently, you have decomps, disassemblies, and PC ports. Those generally require the original ROMs just to extract the assets, and decompiled code does not count as original source code in legal terms. A lot of replacement engines for PC games pretty much do the same thing for the same reason. So, Nintendo can't do much about those.
@ryo @TerminalAutism @Alex Toby Fox (of Undertale fame) used to be an Earthbound/Mother 2 ROM hacker, yet Nintendo doesn't seem to care about his past and let him publish Undertale on Switch and have Sans be an DLC Mii costume in Smash Ultimate. But to be fair, Toby doesn't seem to look at those ROM hacking days fondly.