It started with friends at home. Now Dungeons & Dragons is in its stadium era.

For years after it was invented in the 1970s , Dungeons & Dragons remained a niche game that people – stereotypically, nerdy boys – played at home with their friends.

But in the past decade or so, D&D has emerged as a popular form of spectator entertainment, with comedians, actors, and podcasters playing the game for other people to watch. "Actual play," as it's known, has attracted millions of viewers online, and has even spilled out into the real world, with D&D shows playing in movie theaters, touring globally and selling out stadiums.

One of the most iconic examples of this phenomenon came earlier this year when the show Dimension 20 sold out Madison Square Garden in New York. Roughly 20,000 fans showed up to watch seven comedians perform D&D, with a few rock show flouris