Hey everyone, I have been waiting for a thread like this. Hopefully this continues to get updated and act as a resource for those of us who prefer this stuff. You really have to do a lot of legwork to find good NTS games because even when this content exists it either isn't tagged (people seem to not use the swinging tag much even when appropriate) or lumped into NTR despite it being NTS for sure. Either way, good stuff, you covered most of the very best in the genre; to help everyone out here are a bunch of games not listed that might fit your criteria. Also some of these games kind of suck in my opinion but obviously that's subjective so I'm just going to list what I'm aware of whether I like it or not since someone out there might be into it.
Anyway, if some of these don't fit, no worries, don't list whatever doesn't line up. Hopefully you guys will find something you like here. I'll try to write why I included each but it's mostly from memory so I may get a detail wrong here or there:
Rise of the Crime Lord - Main character is married. Very long game with tons of content and pretty decent story. Wife has a cheating branch but you can keep her faithful while doing a bunch of swinging content with her involving other characters.
Club Detention - Structurally similar to Secret Care Cafe but with traditional western DaZ models. Teacher essentially runs a brothel and pimps out his students to patrons with a management minigame included (like SCC). I think it fits in this thread though because you can formally date some students and there are sharing scenes with them along with a ton of dialogue about watching these girls with other men. Neither NTR nor Sharing are tagged on it but it's there.
E-Thots - This one may be a stretch. It's HS (but so is OnlyHer which is on here) and although it's labeled as NTR, it's sort of a grey area because the MC is fully aware of what all the girls are doing and either encourages it or isn't particularly phased by it. MC owns a modeling agency and employs his sister, girlfriend and childhood best friend. It's light on content for now but has a unique interface and some decent mechanics.
Memories - Very early on but another "husband and wife explore sexuality" game; there are going to be both cuck and sharing paths it seems. It's off to a pretty good start and I imagine after a few updates will have all the content this crowd is looking for.
Exploring the Big Apple - Another husband and wife tale with the focus being on the wife being shared.
Winter Warmth - Probably more NTR and definitely more of the "heading there" portion, but I think this is worth keeping an eye on. Yeah the game's progress is super slow but there's a lot of dialogue hinting at the husband watching the wife with other men and the promise of the dark path has always been corruption and NTR stuff so I imagine it will get there eventually. Not even remotely fully cooked but one to maybe watch very long term.
Harmony Haven - Very early in development, but it has all the ingredients someone in this thread is probably looking for. Husband and wife move to new area with cheating and sharing paths built in via stats.
Naughty 40 - Another "husband and wife sexual exploration" game. Great renders, slow development but there's already a full swinging scene early and it has all the right ingredients.
Thot on Trial - Another "couple explores sexuality" game. Seems very NTR but tons of seeds are planted (including in the overview of the game itself) for it to be a fetish for the guy and not just a dude getting cheated on. Good renders and early in development but one to watch I think.
Lisa Total Investigation - Pretty lengthy game with a ton of content. If I remember correctly there are a few different paths and a ton of ways you can share your girlfriend with all sorts of people and a huge variety of kinks.
Family Vacation - While not the main focus of the game, I'm pretty sure there are good few swinging scenes with the wife and could be more in the future.
Nataly's Route - Very unique in that I think it uses The Sims instead of DaZ or HS? Either way, boyfriend is turned on by thought of girlfriend teasing and doing stuff with strangers, very early in development but seems like it has all the ingredients.
Agent17 - This one is a bit of a stretch admittedly, but I think this game is fantastic. It is HS, but the renders are great and this probably has one of the best sandboxes in any VN I've played. The LIs are really varied and just about every single one has a branching path (very similar to Photo Hunt) which usually go between Love and Corruption involving a whole bunch of kinks. The reason I include it is although some of the Corruption Paths lean heavily towards NTR, there are a few that will be centered around pimping out girls and sharing them. I think most of the real NTS is yet to come, but still figured I'd give it a mention.
College of Mysteria /
My New Girlfriend /
Moonripple Lake /
Shadows of Ambition - Wasn't sure if you were really doing 2d stuff but I saw Seeds of Chaos on the list so I guess I'll mention these. All of these are part of the big wave of AI NTR/NTS games. The art in these four is all incredibly similar, but good. Some written better than others, but if nothing else they all fall under NTS I think. A couple of them aren't too bad actually.
My Italian Slut Wife - Name says it all.
My Loyal Wife - Fairly new NTS/NTS game about husband and wife in a world with almost no women.
Innocent Au Pair Restart - Married guy has nanny; admittedly I didn't get very far in this. I didn't love the sandbox and couldn't get into it last I tried but it has the "swinging" and netorare tags so someone here might check it out and like it.
Great NTS list, but you should add
A Perfect Marriage. Its a twisted game because the FC thinks MC cheat her but he didn't. Then she become more open and has an affair with the best friend´s MC and something with other characters (including an old man). It's a game under development but I've never play something like this. Anyone knows a game like this?