I thought that NTR game is quite common requirement if you're NTR fan in general.
I disagree (not because your wrong) but I believe the wider community is exposed to NTR via illustrations, KP! screenshot stories and manga/doujin or anime as its just one click away and more prolific.
Eorge games are niche and require more then just pulling your pants down, but actual time investment. I have legit 30 eroge games installed waiting to be played - I want to play them all but HOLY hell do I have a lot of stuff going on looking for my time as most of us do. So for most people a picture is there go to NTR.
I'd argue that NTR has changed a lot because of this, back in the early 2000-15 , NTR was literally about the emotions of having your loved stolen or brought to a pleasure the main character didn't - and be utterly destroyed by it.
Yes there was different types, like seeing her pleasured, the feeling of humiliation of that. The difference was that the woman was very much not "wanting" her husband to know or witness it. Unlike cuckold porn where they both do it for each others pleasure or to rub it in each others face. NTR is about the emotions of defeat and pleasure.
Cuckold porn is about the pleasure of denial in a threesome which all parties have agreed to - ntr is not about agreement lol. Netorase falls in the middle, but its meant to be a "bad" fetish not something a couple should want because its based on base elements of emotional NTR.
In the last few years I've seen these lines get more and more crossed, NTR has less build up and any male "love interest" is just an after thought. Its become more about turning hot anime girls into cock sluts with netori men (usually ugly, old or undesirable men/players) then actual NTR.
I believe interracial/black NTR is popular now because of western audiences, which is mostly fan art and SFM NTR. Most western artists are first exposed to cuckold porn featuring black men before NTR or they assume they are the same - lets face it, cuckold porn is all over pornhub. A lot of western NTR fans dont' know the difference between cuckolding and NTR. So by extension most western audiences are coming from sources other then NTR games like pictures or vids, they then combine what they know already of porn into NTR changing it.
Whats interesting is before in JAV interracial porn was considering the LAST resort for most AV actresses, like end of your career desperate - or your a total unknown. It was considering humiliating porn to watch an actress be used by blackmen which is why people bought it. This has vastly changed in the last 10 years, now NTR interracial JAV has totally become a thing. The black westerner stealing the beautiful japanese wife from her husbands bed but its STILL stealing.
I think because cuckolding porn has started to influence japanese audiences as western audiences flood anime channels with it, it moves NTR further away from emotional aspects especially as fewer people play games that require a connection with the character and just getting off seeing a girl become a slut now. Hell one could argue this is because a lot of young people don't even know how to be in relationships anymore and are just used to using one another.
So maybe NTR is changing now based on the generation consuming/making it, where it is less about the emotional loss and more about voyuerism.
Finally I'd argue the majority of NTR games are still played mostly by Japanese audiences. Hell I've had people write me about my Marina project who MIGHT have played the first english translated game but are more excited about it simple because its a NTR english visual novel game and have never played any other Marina game. A lot of people just don't want to bother with translation programs either.
