China’s online gaming industry is worth $13.5 billion and spans 190 million people, from mini-games on WeChat to MMOs at internet cafés. At Chongqing Energy College, people can even take a course in one of China’s most popular online multiplayers – Defence of the Ancients.

As internet-connected video devices become more widely available, there's a growing trend for live-streamed gaming. Platforms like Twitch are creating peer-controlled channels brimming with engaging user-generated content.

In October 2014, tens of millions of people across the world tuned in to live stream a sporting event. But it wasn't American Football or soccer, it was watching two teams - one Chinese, one Korean - compete in the computer game League of Legends.

PewDiePie is the most subscribed channel on YouTube, and its creator makes more than £2 million a year on ad sales. He's one of YouTube's elite – a new generation of hyper-influential media moguls. But why are 30 million teens watching a stranger play video games?