Hey, welcome to the site. It doesn't matter if you call them storygames or CYOAs, the members here use both. There aren't many things you aren't allowed to write, just avoid plagiarism, porn and warrior cats and you'll be fine. And don't publish any really awful stories, obviously. For more information you can check
End's article about (im)mature story writing and
the minimum site standards. Please note that the second article is a bit outdated and the first criteria should be: After receiving at least 10 ratings and being published for at least 3 days, the storygame is rated 2.4 or less. (Though this is flexible if it's particularly bad and still in the 2.5-2.9 range). Use common sense and you'll be fine. Good luck with your story, don't be an idiot and have fun!