We're currently working on a very bloody and somewhat gory game and even thinking of adding in vocal swearing but I'm not sure just how far I can take the violence and swearing while still letting it be published on the app store. The game is sort of road rash with zombies thrown in for good measure, there will be a lot of blood (even more than the video linked) and the aforementioned swearing. I'm not against age restrictions but how bad can a game get before Apple decides it's too much to be on the app store at all?
In my game, Pocket Ninjas, the player can completely dismember the opponent (you actually get extra points for decapitations) and Apple hasn't had any issue with it so they seem pretty relaxed on the subject.