It is difficult to define what ‘Second Life’ is. Its creator, Linden Lab, however, has been fairly clear about what it is not: it is not a game.

‘Second Life’ allows users to create avatars and connect, build, buy, and sell in a 3D virtual world that persists online. It was launched in 2003 and organisations such as Harvard University, Nasa, the Swedish government, the news agency Reuters, and Burning Man all extended their presence into ‘Second Life’. Today, it is something of a ghost town. Although over 50 million people have tried using it, ‘Second Life’ peaked at around one million users and retained around half a million monthly users for most of its lifetime.

This is one vision of the metaverse, as envisaged by Neal Stephenson in his 1992 novel ‘Snow Crash’ as the immersive successor to the flat internet. It was, however, far from the first.

In 1978, Dr Richard Bartle co-wrote the text-based virtual world ‘MUD1’. He believes the long history of...