Four-sided bandit A DECADE ago the idea of paying real money for virtual items was strange and exotic. These days many video-game publishers build their business models around it. Some of the world’s biggest games, such as “League of Legends”, cost nothing to buy. Instead they rely for their revenue on players buying things for use in the game, such as new characters to play with or costumes to put them in. A new twist on that model has been attracting the attention of regulators in recent weeks.