Random_Coffee: The Rance games are my favorite NSFW games overall. Good RPG mechanics and combat, a loveable cast of characters, dark humor, and a great soundtrack. I think they are all worth playing.

Saya no Uta is a great, disturbing horror story with a great soundtrack and atmosphere. Pretty short, maybe 6 hours.. but well worth it.

The best Kagura game in my opinion is Dungeon Town. A pretty standard dungeon crawler, but there is plenty to do, and the gameplay is addictive. Has a nice game world as well with plenty of locations to explore.

Leroux: "NSFW game" is a funny term, if you take it literally. Makes me wonder what kind of relaxed jobs you guys are working in, when the only games you don't want to be caught playing instead of doing what you're paid for are porn-related. ;)

Darvond: The games I'm thinking of are incidentally NSFW, not thematically.

And I can't think of any either unless Dwarf Fortress's god tier gore descriptions titillate the guro fans.

BreOl72: Banging that hot little brunette from accounting in the copy room, without getting caught.

milkyhighway: I might have misunderstood, but I've written this list omitting VNs since I got the impression you were looking for titles with gameplay, correct? (If you want VNs too, I can write up a list of those later)

My top recommends:

Abaddon: Princess of the Decay
A bisexual's paradise, this thing has all sorts of pairing configurations: MxF, FxF, MxM, 3P. (You can turn the MxM scenes off in settings if that's not for you)
Great characters and story, great horror, no stupid jumpscares (as far as I've played), drip feeds you disturbing lore. Heavily inspired by the old Famicom game "Sweet Home"
Very gameplay and story focused. There is a lot of H content but it will take a while to get to it, and requires a *lot* of replaying to get it all. Also, you can choose for the H content to be in HD illustrations, or pixel art to match the rest of the game.

Heart of Darkness
One of the most polished titles published by Kagura. Does very well to capture the dark, decaying, and depressing vibe of the Dark Souls games (if it wasn't obvious, the DS series heavily inspired this one). Interesting story that isn't spelled out for you, instead you piece it together as you play, if you pay attention.
More focused on gameplay, has limited H content. Also, H content is divided into plot and non-plot scenes. The non-plot scenes are soft/sweet/kinky, easily accessible, and involve the main character. The plot scenes deal with dark themes, are avoidable (unless you're trying to discover all lore), and involve only side characters.

Magical Girl Celesphonia
You said you already know this one, but I'm listing it for others who don't know it yet.
Great freedom of choice, and having your RPG character develop in a way that reflects the choices you made.
Lots of H content, doesn't take long to get to it and it's easily accessed. Some rough themes in its H content if you fail/lose/make a bad choice.
If you like it, you should know the developer's next game has been picked up by Kagura Games for an English release.
And the dev's first game, Ambrosia, is already translated (it's here on GOG too). I haven't played it yet but hear it's like an unpolished version of Celesphonia.

Succumate
It's very short but the life sim aspect was fun. It's got an interesting story too, with some unexpected twists at the end.
Plenty of H content and easily accessed. All content is consenual, but there is one heroine which involves stealing her from her partner.

LynXsh: right.
I mentioned The Last Sovereign, but didn't provide the link, now did I?
here: https://the-last-sovereign.blogspot.com/

cons:
- still WIP. sooo it's unfinished ATM and rough around the edges sometimes;
- heavily uses stock assets.

pros:
- the story. no, really. "Came for porn, stay for story.";
- characters are memorable;
- it actually is a JRPG with management;
- H-scenes are justified plot-wise and nice;
- still WIP. sooo more content to come!

Homnavatar: My thing with unfinished games is that I simply never buy them. I'm at a point in my life that I don't NEED to get a game immediately. I can even wait 5 years, just give me the finished product.