It occurs to me why there is no '8' for Maturity Rating on the site (the highest it goes is 7) and it makes sense.
As outlined in the Terms of Service, this is an 'all ages' friendly site and pornography is expressly prohibited. A Maturity Rating 7 is equated to a Rated R movie, so by extension, an 8 would be X-Rated.
There is no Maturity Level 8, because this is not a totally free-for-all writing site. There is a line of what is appropriate and what is not.
You could (like an R-Rated Movie) describe a sex scene, but you would ‘show’ boobs and sensual motion and all the loud caterwauling of ecstasy that goes with it, but not aroused male body parts, penetration, or bodily fluids flying across the ‘screen’. Those type of things belong in an X-Rated Movie/Story and there are other (more appropriate) web sites for that sort of thing than here on ChooseYourStory.com.
With all the talk of Pedo/Incest/Rape based stories happening in the forums right now, I just wanted to point this out. You could write a story about such a thing, but you would have to be careful about your level of graphic detail.
As for using EndMaster’s games as a guideline of what you can and can ‘get away with,’ I think some of his games cross the line in a page or two, but not throughout the entire stories and those short snippets are not the focus of the entire story and are written well enough to convey the situations without being something straight out of ‘Letters to Penthouse’.
So anyway, there you have it. Mods are free to confirm or deny the correlation/causality of the Maturity Rating 7 and lack of an 8…