Community standards apply to all Play by Post games hosted on the Atlas Games Forums. For a reminder of those standards, see https://forum.atlas-games.com/t/registration-agreement-terms/1595/1
In general, possibly offensive material may be "mentioned" briefly, but should not be dwelt upon. Nor should a game be based purely on such. For example, torture was a reality of the Middle Ages, but Ars Magica is not a game "about" torture, and the sagas should not be either.