Answered from a true mom:
A game that gives my 14 year old work a mathmatic equation before he saves the world from destruction. Then forces him to read a stimulating, yet challenging chapter on anything unrelated to sporting events. It has to be a game that grades him at the end and if he doesn't make at least a B, will not work again until he brings his grade up.
Ok, it's a stretch, I know. If my kid were to answer this question, he'd go with Black Ops 2 as well. :)