Nope. The only rules we have are:
No smut between 18+ and 17- members. (Because of sex laws)
Characters under the age of 13 can't be put into sexual situations. (Because of child porn laws)
And I think that's it. Violence can be played between any members, and be as gruesome, gory and violent as you wish. No restrictions. At least not before there comes a law restricting us.
If you want to be nice towards readers though (when roleplaying in the public forum), you can put the more gruesome stuff into spoilers, or write a warning in the beginning of a post that has more violent content, so people can get a bit of a heads up beforehand. But it is in no way required.