On a recent Sunday evening in Beijing, a few minutes before 8pm, Huang Chong opened a Harry Potter video game on her smartphone and tried to play. She couldn't - by government decree. A pop up appeared on her screen: "Dear players… Minors can only play online games between 8-9pm on Fridays , weekends and national festivals and holidays. Please arrange your playing time and have a rest." New rules in China mean that under 18s are only allowed to play three hours of online games per week, at those time specified. Image: Huang Chong and her father Huang Wen...