Flickr was a side feature of a failed game — the game was shelved, the photo tool won

In 2002, Stewart Butterfield and Caterina Fake founded Ludicorp in Vancouver, British Columbia, to build a web-based massively multiplayer online game called Game Neverending. The game was an ambitious virtual world where players could interact, trade, and explore. Development consumed most of the company's resources for years.

As a side feature for the game, the team built a photo-sharing tool that let players exchange images. The tool was originally a minor part of the game experience — a way for players to share in-game moments. But as the game's development dragged on, users outside the game started showing interest in the photo tool itself.

Ludicorp launched Flickr as a standalone product on February 10, 2004. The photo-sharing site grew rapidly, attracting users who had no interest in Game Neverending. The game, still unfinished, was quietly shelved. Yahoo acquired Ludicorp and Flickr on March 20, 2005, for an estimated $22 million to $25 million.

Stewart Butterfield would later repeat the pattern: he founded Tiny Speck to build a game called Glitch, which also failed. But a side feature — a team chat tool — became Slack. Twice, Butterfield built a game that failed, and the side feature became the real product.