By 2020 more than half of American children under 16 played Roblox, according to the company's own filing. Roblox was a giant platform for games. Players built worlds with its free tools, and other players visited them, spending a virtual currency called Robux. Some young creators earned real money. When Roblox listed its shares in March 2021, a year of lockdowns had turned it into the place where many kids met their friends.

A Physics Lab for Kids

David Baszucki and Erik Cassel founded Roblox in 2004. They had earlier built software that let students run physics experiments on a computer. Roblox grew from that idea: a world where things fell, rolled, and crashed, and where anyone could build. It launched in 2006. The bet was that players would build more games than any studio could. Roblox earned money when players bought Robux and shared a cut with the creators whose games they played.

A Direct Listing

Roblox skipped a traditional IPO and chose a direct listing on the New York Stock Exchange. The exchange set a reference price of $45 a share on March 9, 2021. The next day the stock opened at $64.50 and closed at $69.50. Roblox raised no new money in the listing, and existing holders could sell right away. The company has kept growing its audience and adding older players. It still trades on the NYSE under RBLX.

Cover: The Toy Seller, illustration for The Fresh-Water Clam (Shijimi-gai), Katsushika Hokusai. Art Institute of Chicago, public domain. Chosen for a toy seller (a world of toys).