412: The voodoo sex doll. Protagonist uses a sex doll such that when he puts something of a girl's on it, (strand of hair, photograph etc), then any time he fucks it, the girl feels it / gets impregnated.
413: The dominant partner in an established relationship fucks the submissive into a mindbreak state, leaves for whatever reason, and then a third party finds the submissive and takes advantage, only getting away with it because of how thoroughly sex addled the sub is.
414: A group of girls discovery that not only is their roommate a telepath but when they orgasm everyone in the building experiences intense orgasms as well.
Or c) There is no single solution in the world and different nations or zones have implemented their own rules. In some men are the masters and each have a harem of women, in others women have taken over and the men are held in brothels/breeding camps. Some zones cling to freedom of choice with men and women still equal in rights, men would still be highly prized but would likely be wooed by the wealthiest or most powerful women.. In others gangs of women fight and raid one another over the few men. Some zones may have turned against men completely and reproduce by some sort of cloning and any remaining men are hunted down and sterilised/exterminated.
415: Another Sunday Morning. For the third Sunday morning in a row, Claire wakes up naked in the park. Her pussy and anus are always sore and there is always dried cum around her mouth if not on her face and tits. She has no memory of the night before, and is not pregnant, nor has any STDs nor is she ever hung over. Hoe does she piece this mystery together?
416: The Cuckqueans of the Cul-de-sac. On Stepferd Circle, a cul-de-sac in a very upscale neighborhood, a group of mysterious women fuck the men in front of the men's wives, who can do nothing about it.
417: Reverse Isekai - A male fantasy world character finds themselves trapped in our world where his magical powers make him a sex god.
418. Free-use / Time-Stop - Magical Camera phone app. When protagonist uses camera, he gets to enter the picture he has taken. Everyone in the picture is frozen in place but him, allowing him to Time-Stop fuck people. Only the eyes move in the phone app world, showing that the people in the pictures are aware of what he is doing. He can also use the characters in the photos as a source of information to use back in the real world. (eg he can look through people's bags, read their phone texts to use as blackmail material for instance).
419 - Reverse time stop free use. A woman finds herself stuck in time with time moving at a rate of one minute around her for every second she is stuck. By the time a minute goes by to her a whole hour has passed and thirty seconds to her is a little over a day to the rest of us. She is helpless to stop anyone who wishes to take advantage of her and finds relief only during the few minutes of nighttime.
420: Happy Fuck Day! A man relives the same day every time he wakes up. He realizes he can do anything to anyone and even if he's killed, he will wake up and start all over again. But is he the only one, and how long can this go on?
421: A young D&D enthusiast in college responds to an advertisement seeking a dungeon master only to meet the woman who placed the add and find out she doesn't play D&D but is interested in dungeons.
423: 1869 - Following the civil war a young ex-union private is hired to escort a group of women hoping to open up a brothel in the newly established gold town.
I wonder if there would be a way of doing a multi-thread story, multiple authors doing different stories crossing over all based on the same year. (a bit like Marvel's 1602). 1869 seems as good as any. Your idea 423 is just at the time when the first transcontinental railway is complete. Meanwhile the biggest ever gold nugget is found in Australia and the Folie Berger is opened in Paris. Scope for a thread in each of these I think.
"Mon cher, we are having anal sex tonight." "But the butter is too expensive, mais non?" "Have no fear. Monsieur Mège-Mouriès has patented margarine."
424: Peter Parker’s heart raced as he slowly opened the door to his bedroom. He had been out all night fighting crime as Spider-Man, and he was exhausted. His whole body ached with fatigue. But as he opened the door, the sight before him shocked him to the core. In the middle of his bedroom, Mary Jane Watson and Gwen Stacy were locked in a passionate embrace, their bodies intertwined as they passionately kissed and explored each other. "Hello Tiger." Mary Jane smiles.