I don't have any experience with writing stories and I want to avoid cliche or unrealistic stories as well as cheesy characters, so it's best if it's done by someone with more experience in this field.
Hey.
Good for you. Self awareness is a quality gone extinct these days, so it always sort of pokes its perverted little head out, trying to catch a fresh breath of something else along the way, just so it keeps its bruised, puny heart beating for as long as it can. It sounds dangerously like a living thing because it is one of the most organic, morph-susceptable states of mind out there. One moment you can have it, and then...paraphrasing H. Ledger's Joker, "Ta da! It's...it's gone!"
Alright, moving on to more relevant, palpable matters, it's really not that big of an undertaking. It surely looks like it because of all the failed little brothers that we keep seeing around, in this incest-lite direction these so called "games" have taken, but by no means is it something impossible. It's difficult because people make it difficult. The best things in life are simple, yet people are ashamed of that primal state of just...enjoying and accepting their natural place, and in turn, twist those things to appear more complicated than they are.
Calling back to another post of mine, on a similar topic - good writing is hard. Especially for most of these developers, who slobber over their Cap'n Crunch bowls while thinking of ways to figure out how to blue ball people to stuff money into their patreons, proud of the monthly (if that), sad excuses of "content updates" they barely manage to squeeze out of their blemished little butt cheeks.
You see, with "games" like these, with such contexts, they ought to be built on a solid foundation. Sexual tension and build up are the bricks of the incest house. As I'm sure most of us have witnessed, most crumble after the deed is done. Can't even say crumble, as most just fucking end. The sex being the final act, however long or short the time you invested in getting there was, is just the disappointing symptom of the lack of narrative. It ends up feeling weightless and artificial because it is.
So, what, young son wants to fuck hot mom (who, in most cases, looks like a 20 year old; talk about immersion), mom resists slightly at first, and after twenty fucking "updates", she lets him fuck her, and the game ends. Ugh. That's so shallow my balls scrape the reef at the bottom of the fucking sea. And yet, this what sells, mostly.
It's cuz of it sort of-kind of-but not really- touches people's kinks. It's a tingle. Tingles are good. In numbers, organized and paced correctly. But these sad cases offer just one. And that single tingle is enough to jolt the surface of their kink enough for them to reach for their wallets. Porn is much like fishing. But from time to time, maybe the audience ought to open their eyes and realize they're not actually the ones holding the rod.
Don't get me wrong, teasing is good shit. I enjoy it as much as the next guy. Well, not really, because I only do when it's done correctly, but there's a good, definitive difference between teasing and baiting, y'know?
Tapping back into the context thing from earlier, that's what makes a decent game. Plausibility. Believability.
When you're into a situation, if the slightest thought of "this shit's ridiculous" enters your mind, it breaks immersion, taking you out of the experience. And that fucking sucks. Thinking. Cock killer. Once you start thinking, attraction fades away, and your carnal instincts log off.
If your porn, whatever it may be; movie, video, scene, comic, visual novel, game, book; gives you a window to actually think about it, even for a small window, it failed. Why? Because the narratives weren't fully there to begin with. You watch a 20 minute video like this: you watch the beginning for half a minute, to lick what little context of the video there is, then you start skipping through it, to find a couple scenes your dick jolts at, then you jerk it, and that's it.
No one cares about the "story" because there isn't any. With it being a visual medium, you can't even make the excuse of filling in the blanks with your imagination. It simply isn't there.
With these pseudo games, it feels like there's more story to them because you're controlling the character and it brings you under the illusion of involvement. It's a great thing, for videogames (not just adult ones), that they can turn the viewer into an active participant rather than a passive witness (movies, videos). But sadly, that's where the magic ends. That's the extent of the control you're given. And the, what's next? Oh, yeah, you have to grind for thirty goddamn minutes, doing unrelated, uninvolving "RPG-like" activities, to get your reward, which usually, is a tit. Like dangling meat in front of the hairy mutt of a dog, we're mesmerized by the need to see more than a tit, and twenty updates later, we see the second breast. Yoo-fucking-hoo, am I right?
-shakes head in disappointment-
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I just...hate to see wasted potential, y'know? It's such a tragedy, man. It is.
Now, you said "a dialogue based game like with stats, relationship levels, items, etc so they can come useful in the storyline." That's fine, as long as you don't do what I wrote about up above. If you don't do that, you're already one step beyond most everyone else.
Now, depending on what you've played through, wrote yourself, watched, or read about the incestual medium, you're probably going to have your own perspective on what you deem feels "just right", in terms of narrative, so figure out exactly what that is, and try and see why that is.
I'll give you an example. Like I said above, usually, the boy fucks the milf, and the game ends. Sometimes it ain't even that clear they're related at all. All the focus is turned to the gameplay grind, and the fuck itself, that there's nothing else to hold up or to contextualize the dynamic.
Say you go out, and seduce yourself a woman, or a man, or whatever fucking attack helicopters people sexually identify with nowadays. You go wherever, you fuck her, and then you give her money for a cab. You've satiated your carnal need, and off she goes. Although, in this case, "she" is too much of a description. It is much more fitting. I mean, that's what it was. You didn't give it any chance to be something else, or something more. It was just some meat you felt attracted to, in which you put your cock in. That's fucking. Fucking isn't bad. It's alright. In some cases, women will even tenderly whisper in your ear as they bite on it "Fuck me. Hard." And that's good. You should do that. It's healthy.
But, you see, sexuality and biology is more than that.
"Everything in the world is about sex. Except sex. Sex is about power."
In no particular order, there's a few dynamics at play here.
There's fucking. You fuck her, or she fucks you.
There's sex. That's better. That's like a team, or the gears of a mechanism, trying to spin around in the same direction for optimal efficiency.
There's the ever so romantic "love making". That's sex plus emotional context. But there's something wrong with that. It feels...artificial. Constructed. Defined. By us. By people. It feels unnatural because we're trying to make it unnatural, either less than, or usually, more than. People are so obsessed with beating nature at its own game, and spending their lives priding themselves on being more than animals, they drown that sexy fucking feeling of self awareness at the top of these paragraphs I spoke about, they push it down, until it turns into something else. Until they forget that, at the end of the day, the things that truly make people happy are the things that made us happy thousands of years ago. The things that make a man happy are no different than what makes the lion happy (wonder why we gave him a moniker such as "the king"). Or a bison. Or a tiger. Same for women.
Everyone's running away from their animalistic nature so much they forget about it. But, at the end of the day, when the sun goes down, and it's just you, and someone else in a dark room, what do you feel? Barred of social constructs, romanicized descriptions, or colorful words, you feel...natural. Well, feel that. Revel in it. You don't have to ask for permission to feel that way, because you are that way. There's a female and a male in that dark room, and they want to do what nature engaged them to do. They want to mate.
That's a word. Mate. When's the last time you heard that? Certainly wasn't yesterday. It's surely not mentioned on the news. It's written on people's shirts, and it definitely doesn't go around people's lips in whatever venues people meet in nowadays to uh..."socialize".
We've excluded it so much from our lives, our vocabularies, that the mention of it makes us queezy. But not bad queezy. No. Makes us wonder. Why don't we use it more often. It so perfectly describes one, if not the favorite thing that we do. We stopped using it so much that know it sort of has a forbidden-like quality about it. And as animals, the dark sure as fuck entices us.
So, it just a word. First it was "making love". It felt wodden. It felt safe. Then, it was "mate". It felt natural. Organic. Right. That's the difference. That's what narrative is. Context. Sexy, I know.
This what you need to do. Just like you colored your artwork -- which, props where props are due; for once, the mother actually looks like an adult female. I'd give her some pubic hair, though. Not much. Just enough that when you look at her, you don't see a 12 year old girl (I'm sure there's games for that, too.) -- Color the narrative, as well. Color them, y'know?
She's a single mom. Why? Where's the husband? Is there any? What's their relationship? Before a mother, she's a woman. What kind of woman? Is she confident in her life? Is she satisfied with it? Maybe. Or maybe not.
What about the boy? You've drawn him pretty young. What's he like? Does he like his father? Does he not? What's his interests? He can't possibly be a dick with two legs. Sure, that's one of main driving forces behind a growing boy, but it ain't the only one. Define him more than just "I wanna fuck my mom". On top of that, what's the relationship with his mom? Does he like her? Does he dislike her? Why does he want to fuck her? Better yet, does he want to fuck her, or does he want to have sex with her. Or does he want something more than that?
A sex scene is easy to write. It's what's around it that gives it quality and authenticity. Especially in a context like this.
Remember that.