In just under two months, a Roblox user-created game called Grow a Garden has become a massive hit.

Like YouTube, Roblox started as an online stage for young creators. As the company grows toward 100 million active daily users, contributors are making big money selling games.

Roblox is a huge sprawling world of games which is sometimes described as a kind of primitive metaverse. It's one of the most popular children's games in the world. The exact figures are a little ...