Bono has developed a reputation as a rock star with a conscience. The leader of the band U2 has cofounded two lobbying groups that raise awareness about Africa’s afflictions, created a fair-trade clothing company, and brokered a deal with several major American companies to donate millions of dollars to the Global Fund to Fight AIDS. But now he is caught up in a controversy over one of his own ventures. Dozens of organizations are asking Bono to stop production of Mercenaries 2: World in Flames, a violent video game in which players become hired mercenaries who invade Venezuela, where a...