As a baseline dnd 5e will be used. with that said i plan on using a handful of homebrew mechanics. first during character creation each player should pick one fetish to have, one to hate, and roll on a table (to be made) for a second one to have. I may abandon the rolling being required and just let people roll if they want.

Besides this i think the primary function of the fetishes is that they will give advantage or disadvantage on arousal checks, which must be succeeded on for males to engage in sex, or for females to orgasm from it. The arousal check will be a Con check, with no proficiency modifier, the only thing that i can think on to effect it is either fetishes or situational advantage or disadvantage. (I like using those, so they should happen decently often.)

Another homebrew mechanic im thinking of using is codifying forcefully undressing and fucking an enemy in combat. What my thought is, if you have successfully grappled an enemy, you may use an attack action to remove their clothes instead of dealing damage, when you do, simply make another grapple check with the victim, and if you succeed you undress them, if they succeed you do not, but they stay grappled. 

The next mechanic is that of fucking someone in combat, if a is functionally nude, then an action may be used to fuck them by any creature within 5 feet of them. Note that if the creature is unwilling then they must be grappled to do this. 

Also all monsters will be able to grapple now. and some monsters will be changed so as to be better at raping women in combat.

If anyone has any issues with these they are of course cool to be changed.

Woman is double teamed by a pair of monsters

Party of women are gangraped by a tribe of goblins

Woman is overcome by a horse

If a player chooses to be a futa she must keep this a secret, or she will be enslaved and taken to the queen of Rapia.

In addition, if any women are found to be harboring any futas from the law, they are also enslaved on the spot, and given over to the King and Queen for punishment.

Elven Inquisitorial forces have a presence in all humanoid civilizations to uphold these laws.

Futas being tormented in the Queens dungeon:

Culturally the Elves are by far the single most debauched society in the world. They are immortal, and therefore know the nature of the gods, and follow their will. Therefore they practice widescale female slavery. All elven women are enslaved at the age of 18, often by their fathers or brothers, and they practice an extensive slave trade with human cultures, buying 1000s of human women to desecrate as they see fit.

Murder and Theft are seen as wrong in Elven society, but rape, incest, and bestiality are seen as completely normal.

At the center of Rapia is the palace of the High king and Queen, which is a massive sex dungeon. It is considered a great honor for a women to be taken there, but she will be tormented in ways unheard of outside the royal palace.

The King and Queen themselves are siblings, bound under the same laws of slavery as any other woman might be in Elven society. The King is the absolute ruler, and the Queen holds absolute authority over women.

Dark Elven Sisters being used in the street

An Elven girl celebrating her 18th birthday with her father and brother.

A group of human slaves waiting to be auctioned off

Goblinoids (Orcs, Goblins, hobgoblins) would all behave similarly to what is expected of them. They all often raid Human, Elven, and Dwarven settlements, trade caravans, farms and the like, killing all the men, and enslaving all the women.

Goblinoids generally have no issue with murder, as long as it was a goblinoid committing it. Goblins are ok with theft, but orcs and hobs would prefer their people murder each other than steal. Rape, slavery, and bestiality are necessary to all of their cultures, and they usually keep large pens of chained up Human, Elven, and Dwarven women to use as breeding stock for themselves and their mounts.

Incest is of little concern to them.

Any intelligent monster that keeps communities may be assumed to behave like goblinoids.

All unintelligent beasts may attempt to catch human women unawares and have their way with them, but they will also attack caravans, small towns, and adventuring parties, slay the men, and rape all the women, leaving them pregnant.

All beasts (wolves, bears, wild horses) simply seek to catch humanoid women unawares while they stroll through meadows or forests, having their way with them and leaving them pregnant.

Below are examples of how Orcs, goblins and beasts treat captive women.

Dwarves believe Rape, Murder, incest, and Theft to be wrong. With that said, women in Dwarven society are seen as little more than bargaining chips to be used by both male dwarves, as well as any monsters that have something of value to trade.

It is common for dwarves to give their women over to monsters to gain a relative form of peace with them. Dwarves value gold above all else, even over their own flesh and blood. Dwarven men keep their sisters and daughters close, so as to keep them as valuable as possible to a potential ally.

Physically speaking dwarves conform to standard conventions, mostly red haired, short, and stocky. Their females are usually quite curvy.

All Humans hold a general set of moral and societal standards, with any exceptions by a culture being stated in that cultures description.

All human nations do their best to protect their women from being abducted by monsters and beasts. All human nations believe Rape, Murder, incest, and Theft to be wrong.

Most human nations believe Bestiality to be wrong.

There are four human nations that live on the continent of Orone, they are:

Hushul: A fairly standard western European style nation, economy is mostly focused on farming and logging. They are a pale people, with black and blonde hair, and varied eye color.

Yamana: Heavily inspired by Japanese culture. They grow rice, and fish en mass to feed their people. They have dark hair and almond shaped eyes.

Catala: A strange mountainous region, the people of Catala raise and keep livestock of all kinds. They are a pale people, with red hair and green or blue eyes. The people of Catala have no problem with Bestiality, as they must commit this to breed their livestock.

Arstund: A land of great planes, the people here make their wealth from the rich ore that runs under their nation, trading it with their neighbors. The People of Arstund are dark skinned, with dark hair and eyes.

Below are examples of Arstund and Catalan Women.

This setting is intended for extreme fetish play in a tabletop game, as a default it includes female slavery, bdsm, incest, and bestiality. Any or all of these are viable to change at a DMs discretion, or at the request of a player.

The world has 6 major civilizations, 4 human, 1 dwarven, and 1 elven. Besides these races all the other standard creatures exist in the setting, just in smaller numbers, or scattered and underground, as is the case for orcs and goblins.

Halflings, gnomes, Tieflings, Dragonborn, any other playable race from the PHB can be assumed to exist in either small conclaves, or interspersed through the larger societies.

With all that said, the only creatures in the setting that can naturally have female members of their species are the humanoids, (this does exclude giantkin, and goblinoids). To account for this, every humanoid female’s womb can be impregnated by any living things cum, and she will give birth to a male of the other species.

This is the way of this world, as dictated by the Twin Gods.

The Human civilizations shall be fairly similar to standard 5e depictions, as will Dwarven and any other racial groups. The only major exception is the Elves, who, being immortal, Know and follow the will of the Twin Gods to the letter. All elven subcategories are united in this, and all but a small few who leave to wander the world live in the United Elven city state of Rapia.

As to the nature of the planes, I am unsure of the details at this point in time, they will be sexified in some way. And of course, if anyone has any suggestions as to how to handle anything from a thematic standpoint feel free to comment.