I've recently been positively surprised by Officer Chloe: Operation Infiltration (out on 0.6, iirc). It's a bit on the rough side if you don't know what's coming (i.e. it's not your typical light-hearted non-story), but it's written well enough that I actually did a high-morality playthrough to its current end; It also warns you about certain more extreme fetishes, so that's a plus in my book. Even though it has some features that decidedly put me off (too much informal/leet lingo, forced sex), it still gets a recommendation from me - it features remarkably few spelling mistakes.
I'm also casting a vote for Gates: The Opening; As RPGMaker+CG games go, this one has actually decent writing and some interesting characters. You should be aware that some of the stat checks for certain girls can be a bit sudden and non-intuitive (for example: There's a check for high Ego in the Ulya route that took me entirely by surprise, and I couldn't pass it on my first playthrough; issue being that most other Ego checks (and raises for that stat) come from interacting with a girl that's pretty much Ulya's opposite). At the same time, the game is highly linear - if you fail to trigger events at their allotted time, you pretty much fucked up that route in the current build (which only has a few days anyhow, so that might change). I'd recommend having a walkthrough ready if you pursue certain girls. On a big plus side, the game has some time-sensitive decisions, but it has the very good grace to warn you when it's about to start them.
Further, I must mention Summertime Saga: You're a (presumably of-age) dude trying to get his family's financial situation under control while also attending school and constantly being distracted by very nice art (Western Comic style) of actually realistic-looking, huge boobs. Well, semi-realistic. My point is, there's a lot of torpedo tits; But hey, they're my favourite kind, so I'm not complaining. There's also a major focus on incest, a bit of voyeur action, and quite possibly major milking in future updates. It's good and you should check it out is what I'm saying. Heads-up: There's a password to your sister's computer, but as of the current build (0.9c), it makes the game crash.
There's also Valentina's Story, centered mostly around exhibitionism. It's (afaik) currently at version 0.1, but there's enough content for a first and second impression.
Further recommendations (including games already mentioned here and on these fora), from a strict "quality-wise not rage-inducing, might as well check 'em out" point of mention:
- Lily of the Valley. RPGMaker.Centers around a mature-ish woman and her love life, possibly including Nice Time for Roo along the plot, as far as can be made out from what's available. Around 50% done in my estimate.
- Coceter Chronicles. RPGMaker. Fantasy, 'demi-demon explores human world', incest seems probable from what I've seen. Prologue done, short peek into "proper game play" so far.
- Dating my Daughter. The name really is the game. First few days are available, mostly romance options (kissing, light touching), but that's one petal off a corruption meter with around 20 of them.
- Library Story. Corrupt Disney's Belle as Gaston. The early third of content is playable.
- Hentai Highschool. Corrupt an entire school; old concept, but development apparently still is semi-ongoing. Its current version is 1.07, there's a lot of sandboxing and barely explained game play as well as placeholders. Simulates an entire town, with every NPC having its own paper doll and being corruptible. If you're looking for an alternative that's more actively developed, you might give School of Smut a poke. That one doesn't have paper dolls, though, and is as-of-yet quite unfinished.
- Magic Shop, Princess Trainer, Witch Trainer, Star Channel 34. All Akabur games, Ren'Py fare with lots of grind. Corrupt pop culture pures. Quality-wise very good, fetish-wise pretty Vanilla. First three games are feature-complete (with Witch Trainer having a fan mod that adds some content), Star Channel 34 is currently being developed, with the early parts of the game (maybe 20%, if that) being available.
- Play With Us! Short-ish choice-based visual novel about a boy's first experiences. First episode is complete, and features trying to sex up your long-time girl friend. Second episode features incest by introducing the PC's sister into the mix. Currently at 'Demo' status, afaik.
- Seeds of Chaos. You're a fallen hero in charge of preparing your home land for a demon invasion. Intro is complete, first glimpse to game play available. Features decent writing, really good art work, demons, and optional Nice Time for Roo so far. Oh, and I am freaking glad that the Nice Time for Roo in this case is optional, because you're playing the dude getting cuckolded. And since the woman in question hits every.single.one of my "most attractive combination possible" kinks, that ain't happening. Not in my bedroom.
- Succubus Tales. RPGMaker. You're a succubus corrupting a village. First few days playable. It's more of a visual novel than a game, but if you're into the theme of demonic corruption, it may be worth checking out.
- Zoe's Temptations. RPGMaker. You're playing a girl with a faye and a succubus perched on her shoulder, each trying to influence her into acting certain ways. Faye is mostly compassionate, loving ways, and Succubus entails S&M, vindictive actions. Personal pet peeve: Why can't I have nipple piercings without being an asshole, mom? Ahem. It's decently written (made me actually emotionally invested enough to get a game over by refusing to bend to a certain creep), features CGG, a bit of forced stuff ("in over her head"-type), and a good bit of female on female.
Apart from those, most of the games currently in development I've tried that aren't mentioned somewhere here tend to suffer from either a very buggy state, poor (borderline intelligible) writing, and/or dearth of content. And if there's one thing that'll turn me off faster than a fetish I'm not into, it's authors that don't care for their text.
edit: List's not entirely complete, though. There's two more games I would find worth a mention, but I'm not sure if those would be okay since a case could be made that they include possibly under-age characters. One's a zombie-of-sorts, and you're playing him, but still: While there's no explicit mention of his age, he doesn't look 18+. Shame, since the game play itself (survival) would be worth a recommendation in itself.
The second one features an option to restrict "immature" content, and no ages are given, but still: I opt to err on the side of caution.
The reason I'm even pointing to both those is because they're a cut above the usual fare mechanics-wise: Their "game" part isn't merely a vehicle to get to the boobage - it's actually robust enough to be enjoyable in itself.
