You cant keep hiding it forever man,my dad took me to fire a gun ASAP for me to withstand the recoil of one, what I mean is eventualy some other kid is bound to show up with a PSP or 3DS or some other portable, and expose games like Grand theft auto.
Also the rating restriction law was lifted so now a nine year old can walk into a store and buy a rated M game.
I'm not going to tell you how to parent as I am just a mere teenager, you parent the way you think is right, but the only way to censor is to edit textures/replace source files or go buy a foreign version.
Edit:Holy stuff I typed this all with a 3DS!?