Re: Eroge with photographs instead of drawings
There are a few that exist, but to be honest they don't look appealing at all to me.
The ones I've seen tend to be very vanilla, use typical stereotypical porn models, and the gameplay is usually just some simple stripping game of some sort. Or of the "play this minigame, earn a picture gallery" variety.
Real life models are a bit of a dead end in game design. (Hentai or otherwise) Because they're completely non-interactive by nature. There's no functional advantage to using photographs over drawings unless it's a pure artstyle decision, and even then you're stuck basically making a visual novel or something.
The only real strength of real life models is that they're much cheaper to "animate" and you can easily have cutsceenes, but it's difficult to make loops and sprites and 'gameplay" animations, so at that point, you're basically making a movie anyways.
Once you have the budget for hiring actors, equipment, lighting, costumes, photographers and such, if a game is your goal, then you're better off putting that budget into high quality 3d models and animation for a more interactive experience.
And when it comes to porn, if you're just in it for the money, once you have the photo and video that's all you need for a viable product. Turning those materials into a game is more work, less profit, and SHRINKS your prospective audience because the market for straight-up porn videos is much larger than the market for games, so why would you bother? Not to mention, most of the audience for eroge is actually going to prefer art anyways.
And if you want to make an h-game with the same budget constraints as something like an amateur webcam model you basically still have the same problem. Okay, so you have one girl/guy, a camera, and whatever clothes and sex toys they own. How are you going to make a game that's more compelling than simply letting them masturbate or fuck on camera and just selling the video?
I'm not saying it can't be done, it certainly can, but you need to put a bit of effort and creativity into making it special, and have more motivation than simply wanting to make a quick buck.