Greetings.
I thought I make a shortlist of universes that I created and plan to expand in the future by adding more stories that take place in them. Most often I would be willing to let other authors write in them too. Even if there is probably no demand for it. I only listed universes in which I have published at least one story.
Anyway. Here is the list:

0 - Index:

1) Heirloom Gems
2) Undesirable Classes
3) The Totalitarian Society You Will Love
4) Mercy Verse
5) Caves And Dungeons
6) Dimension Mages
7) Fashionable Witches
8) Supervillains Exposed
9) Artifact Of The Ancients
10) Naughty Witches
11) New Terra
12) Maintenance Workout

1 - Heirloom Gems
Released: 5
World: fantasy / soft-magic system
Core mechanic:
Mages created a type of gem that can learn. The original purpose was that a gem can 'learn' skills (even spells) and knowledge when a wearer uses them frequently. Then give the learned skills to the next wearer of the gem. The more owners a gem had the stronger it becomes. Older gems have been known to learn behavior if many wearers share a certain behavior. If all past beholders of the gem had been flirtatious then the gem will make future owners flirtatious too. At last, it was discovered that a gem can learn a body type or body attributes (including gender) and change future beholders to match. The maturation of a gem can be boosted with magic.
Planned future stories: 5
What's the hold up: verse lacked popularity and got a low priority for continuation
Share status: not shared - open to sharing upon request

2 - Undesirable Classes
Released: 4
World: urban fantasy / soft-magic system / soft-GameLit
Core mechanic:
The world is similar in technology with the added attributes of magic and it is governed by fixed rules based on statistics. (An RPG-like stats system) Each person has a class. These can vary wildly. Some are popular. Others are either misunderstood, unbalanced, or broken. These are deemed undesirable by society. Each story revolves around an undesirable class the main protagonist gets stuck with by happenstance. They have to learn to live with it.
Planned future stories: 13
What's the hold up: I am currently trying to write story 5, but the motivation hasn't been there lately.
Share status: not shared - open to sharing upon request

3 - The Totalitarian Society You Will Love
Released: 2
World: Science Fiction
Core mechanic:
Stories take place on a planet called Utopia 3. The colony there is known as The Totalitarian Society You Will Love. Each story revolves around a person who entered hibernation sleep on Earth and was subsequently sold to the colony. The government boasts that they have the perfect place for each immigrant. Settling them into neighborhoods that house like-minded colonists. They are put to work in jobs they would do as hobbies and given everything exactly to their needs. In limited quantity. However, to fit in they might adjust the bodies of the immigrant. But besides that everything is perfect. This is the plot twist of the verse: it is a totalitarian society but no one minds it as it is a perfect experience.
Planned future stories: 3
What's the hold up: all three planned stories need to be developed into proper plot outlines
Share status: not shared - open to sharing upon request

4 - Mercy Verse
Released: 1
World: Urban Fantasy
Core mechanic:
The universe in which "The Lokian Way" takes place. Earth developed differently based on the fact that magic exists. While geography is mostly the same, history differs wildly. The most powerful mages in the world's history are based on the gods of our Earth.
Planned future stories: 3 short stories + 1 prequel
What's the hold up: lack of mood
Share status: closed

5 - Caves And Dungeons
Released: 1
World: Fantasy - GameLit
Core mechanic:
Inspired by 4X turn-based strategy games this world entirely plays underground. It is populated by factions and their sentient units. These units can be captured and converted into units of another faction. If it happens they change into a unit of the same tier of their new faction. If a unit of one faction is one gender and the new unit type of another faction is of another gender a gender swap happens.
Planned future stories: 6
What's the hold up: The universe didn't appear to be popular and sank in priority for me accordingly.
Share status: not shared - open to sharing upon request

6 - Dimension Mages
Released: 1
World: Urban Fantasy
Core mechanic:
The world is an Earth just like ours. But unknown to the general public there are mages that can access and alter unused dimensions to their liking. Either to travel to them or have them the normal Earth in a way. (Magic of an altered universe could be accessed in the normal base world if set up correctly). However, especially young mages are known to make mistakes. Sometimes with unpredictable results.
Planned future stories: 6
What's the hold up: in progress. The released story is being expanded and two other stories have been started.
Share status: not shared - open to sharing upon request

7 - Fashionable Witches
Released: 7
World: Urban Fantasy
Core mechanic:
A world like ours is plagued by "fashion witches". These witches transform victims into sentient clothes in order to bolster their own defense against other witches. The main focus of this world lies not on gender-bending, but on gender-bending being a more favorable outcome than to end up as a sentient piece of clothing. Some witches go the alternate route of building lairs. Trapping souls as animate or inanimate within.
Planned future stories: 3
What's the hold up: The next story is available for voting on the Discord server.
Share status: not shared - open to sharing upon request

8 - Supervillains Exposed
Released: 1
World: Urban Fantasy
Core mechanic:
News articles that highlight super villains that emerged on Earth after an event that gave 5% of all humans superpowers. Most of these abilities are goofy as the focus lies on humor.
Planned future stories: 2
What's the hold up: in progress
Share status: not shared - open to sharing upon request

9 - Artifact Of The Ancients
Released: 1
World: Fantasy
Core mechanic:
An artifact exists that needs one hundred volunteers. One of them is chosen at random to create a new race from scratch. The ninety-nine others are changed into this new race too. Lately, more and more chosen ones have experimented with race types that have a spin on genders.
Planned future stories: 4
What's the hold up: I have started on the next installment but got distracted by other projects.
Share status: not shared - open to sharing upon request

10 - Naughty Witches
Released: 4 (and a half)
World: Urban Fantasy
Core mechanic:
In this version of Earth, magic exists. But a secret council of witches hides this fact. A few other witches try to expose magic to the world for their own gain. As a means to do it, they give inexperienced witches access to spells that are unpredictable, evolving, and often very lewd. Stories in this Verse often feature giving bodily features new and strange magical abilities. For better or worse.
Planned future stories: 1
What's the hold up: NW 5 will be bigger and needs a defined plot
Share status: not shared

11 - New Terra
Released: 2
World: SciFi / Fantasy
Core Mechanic:
Earth had to be evacuated and 2/3 of the population took the offer from aliens to be relocated. They arrived on New Terra. A planet that has 10 times the surface area of Earth. The geography is also oddly reminiscent of old Earth. Soon, the displaced mankind find out that the core of this artificial planet is one giant computer and it can create effects through instinctual interactions with humans. While most acknowledge the science background, this is commonly referenced as magic. 300 years have passed on New Terra and while mankind was rebuilding the pop culture of old Earth has often been elevated to religious worship.
Planned future stories: 12
What's the hold up: The next story is available for voting on the Discord server.
Share status: not shared - open to requests

12 - Maintenance Workout
Released: 3
World: Near Future / Dystopian
Core mechanic:
These stories follow Zane Graves, who lives in a world with a 99% unemployment rate. The 1% who have jobs have more than a few advantages. The existence of souls has been proven and soul transfer into new bodies has been accomplished. As a result, the rich are theoretically immortal. New bodies can either be clones or androids. The latter needs regular maintenance. As Zane lands a job at Castro Analytics, it is his job to "jump" into different android bodies to help them get maintained. However, some of these bodies have quirky mods installed.
Planned future stories: 4
What's the hold up: The next story is available for voting on the Discord server.
Share status: not shared