Nah just straight up husband cheating
Everything cuck/NTR is always the girl doing the deed.
I want that reverse scenario of a dude cheating on his shitty excuse of a wife lol
Never really heard it called that. From what few games I remember where it's the guy cheating, it's still just NTR? I mean, the source slang isn't gendered at all either. While it's obviously almost always a man, you could stay that for a shocking number of kinks. Regardless, I agree that most fringe kinks end up getting to much tacked on as well so it dilutes things. So while you might find an entire game completely or mostly dedicated to something specific, stuff like futanari tends to be a tiny slice with a handful of scenes, and as super_slicer said, there's a good chance it's also going to be hyper or something else too.
On the flip side, I guess you never know. People like to dismissively wave their hands about, say, monster girls, but then point at a completely normal girl with slitted eyes and maybe a scale on her noise with a couple small horns and say "see? monster girl, I'm into that." But then something like Monster Girl Quest or Shrift comes along and has some pretty out there takes on monster girls, and still do explosively well.
So I guess it's really down to presentation. For most people, I feel like kinks actually aren't a hard yes/no, but a gradient of tolerence that ranges from enjoyment, to disinterest, to disgust. Neither guro or vore does nothing for me for instance but I don't mind seeing it and it won't keep me from a game that has other stuff.