es, it's allowed. Yes, your character can swear, kill, and have sex as long as it is tastefully written. Your character can be as vulgar and cruel as you choose. The setting is one of "low fantasy" which implies that it is dark, gritty, and sometimes unsettling. We do not police the content of our forums.
No, this is not an "adult oriented" roleplaying forum. When we say that we roleplay, we do not mean that we are here to write interactive pornography.
Because these things are allowed here you must be at least 16 years old to use Thar Shaddin. If you are between 16 and 18, it would be nice if you asked your parent or guardian for permission. Show them the forums so that they know what you are up to. If your parents would like to talk to the staff or the owner (that's me!) I'm happy to oblige.
Unless you are older than the age of consent where you live (usually around 18), you are not allowed to give out your personal information here.