All in all, I'd say it is already easy enough to get in trouble if you don't actively try how far you can go.
Have an extremely racist main character?
You might get away with that if you have a very good explanation, but it's risky to say the least. Not advisable in any case.
When Samuel Clemens referred to Jim as a good guy although he is only a nigger, this raised a lot of controversy. And that was over a hundred years ago, at a time when people were not nearly as sensitive to that kind of thing as they are now, and Clemens had a "kind of believeable" explanation.
If you plan for open racism in the protagonist (not in the antagonist), best prepare for a lot of hate mail, and plan for interdiction and criminal prosecution.
Show naked children
A naked child (as, for example, on the beach) is a pretty normal thing in Europe (at least it used to be), but a serious affront (close to a capital crime) in the USA or some other places. I would still be careful because Europe is more and more going bigot, too.
kid doing a bloodbath in its school
torture & murder simulation game ? with rape ?
play a terrorist that try to drop a bomb
Almost guaranteed to get you on "The Index" in Germany, interdicted in the USA, plus death threat letters from both rape victims and soccermoms and religious people. Most likely to get 18+ ratings in all other places. And, it's almost impossible to talk yourself out of the situation afterwards.
Also note, that quite possibly the police might have a close eye on you after that. Because, hey, you're obviously a pervert, potentially dangerous, aggressive, and a terrorist who is planning to drop a bomb. And you're encouraging others to do it, too.
And hopefully nobody re-plays your school massacre in real life, or you might be held liable for giving them a detailled how-to and a virtual training ground.
I remember some imbecile called Microsoft Flight Simulator a terrorist tool back in 2001 (though I can't remember who did). Because allegedly, the alleged arabs who flew those airplanes into the buildings used MS Flight Simulator to train (since they died and burned to ashes in the crash and could not be questioned, I wonder how we can be so sure about all that, but... anyway).
Calling Flight Simulator a terrorist tool is of course total bollocks, but if you make a game about doing a massacre in a school, and someone really does this afterwards, it is a quite different situation, and it is very conceivable that you'll be held liable.
I'm from France
Well, as you know, even France isn't what it used to be. As the Conseil Général put it only two weeks ago, they agree with Charente-Maritime's vice-president that attractive young women wearing bikinis are "bad taste".
Luckily they've agreed to gay marriage, now that Marianne isn't allowed to show her breasts -- even wearing a bikini -- any more.