Mahogany, a young mare, bears a terrible curse, laid upon her by a vengeful zebra.

While marked by this curse, she enters a state of constant hyper-fertility. Were a single drop of sperm to touch her nethers, pregnancy would be almost assured. However, this is merely a secondary effect compared to its primary intention: The first male that manages to impregnate her, she will be enslaved to for life.

Now, follow Mahogany's misadventures, as she tries her best to keep her womb from being despoiled. Whether she succeeds, or fails, is up to you.

So, a long while ago I found this story. (It doesn't count as an adult link if it's just text, right?)
And then I lost the link, but I still remembered quite liking the story, so I took the basic idea and built my other story, Game of Estrus, around it.
I then found the story again recently, but by this point GoE has evolved its own identity enough that I don't think citing it as an inspiration is really required or holds all that much weight.

However, much to my dismay, I noticed that the story has not updated in a rather long time with no indication that it even ever will. And so I thought, "Hey, the first story I wrote based on this one was such a huge hit, why not go for a second that's even closer to the source material?"
"Because that's a rip-off and basically illegal?"
"Quiet you, I'm doing it anyway!"
And so here we are.

This story is written in a choose-your-own-adventure format, meaning that at the end of each chapter there are options you can choose to decide how the story progresses.

To avoid overly-long wait times on your favourite branches of the story, I recommend that you let me know in the comments which threads your most keen to see continued, and/or by what options you'd like to be able to take. I'll fill them all out eventually, it's just for efficiency's sake.

And if you have any ideas for new options to branch off from a certain chapter, suggest them in the comments too. You can even write up a full chapter if you like, and I'll probably include it.

Curse guideline for those wanting to write a guest chapter:

When impregnated, the cutie mark of the father will appear in the centre of the horseshoe.
Once you've been bred, you will gradually become the father's slave, as the four screws appear in the horse-shoe's holes. These can each appear anywhere from immediately to a week after conception.
Birth control does not work. Condoms or abstinence are your only salvation.
The curse is contagious, and will be spread to any female you bring to orgasm.