The only one I have seen that comes close is "my girlfriend's amnesia" and even that is not ntr in the sense of the words. Some guy sometimes enters at night to have abuse the players girlfriend who can't remember anything from the day before, but only if the player chooses so. The MC does not see, so it's tecnically not ntr.
If you say that it was a 100% split harem/ntr game, who was taken from the mc? I remember that the original BB always had that ntr shadow over it, but it actually never happened. It was the danger that Max would face if he didn't succeed. All I can think of are a few scenes with Alice on war path if the player didn't buy her outfit and lost influence. Is that what you mean? Or what else was there? The abusive pics with Lisa were fan made.
And no, I have never seen a Eric game myself, but I believe it if someone says that there were attempts to make one.
I am actually not sure if there are ANY non ntr games apart maybe from some hentai VNs (if you call VNs games ...). It's a narrative aspect but for it's nature it's very difficult to include it in a game where the player is meant to do something and maybe succeed.
I think it is fair to say that the NTR in the original was never fully developed. I think it was there though, and you could say the original was an NTR/Harem split route game.
SO much of NTR is the build. The slow corruption. It just never panned out. The competitive character of Eric alone made it NTR. A game set up with a stereotypically more alpha figure plotting and planning to take all the women the MC wants. And, to some degree, winning. That's NTR.
But, on reflection, on some level, I guess you could argue it was never really an NTR game since that plot line was never taken to its payoff. But, I think it was intended to at first, the concept was present, I mean, hell, that's what drew me to it in the first place.
On the other hand, that's kind of mixing causations. NTR was planned, people pushed against NTR, NTR dropped, so never NTR. See what I mean? The push against NTR is what killed NTR, so to use that NTR never panned out to say it was never NTR is a bit circular.
