Anything considered 18+/adult/mature (or whatever noun you can think of to mean "games for grown-ups" covering all genres), it would likely be time to consult a lawyer to check whether the content broke any laws with respect to 'real world' obscenity/violence/incitement/etc., probably more so with anything considered 'adult' in nature (anything that allowed inter-personal interactions) because that type of content is generally policed much more vigorously then others.
However, and in some senses, doing the above would be moot (and potentially expensive) because using a game engine like Unity, UDK et-al means content producers would be bound by the terms of use they 'agree' to when using the available tools; this basically equates to the system provider having final say on the material, and done in such a way as not to create any liability associations from their point of view - they would want to be careful not to give permission of use to content that could bite them in the butt at some later point (adult material is notorious for this, so too anything that has the merest hint of 'terrorist' associations). So whilst as a hobbyist it's possible to be quite blase to all this, the moment you go commercial it's something that has to be considered because the liabilities and potential for being sued increases exponentially.
[NOTE]just a friendly reminder about the words and language we use when discussing certain subject matter. Although it's certainly appreciated that it's tricky to talk about 'adult' material and content without the use of explicit wording (implied or indirect), we do need to keep in mind the forums don't have any access restrictions in place so can be viewed by a broad range of visitors.
