In 2003, three university students in Finland, Niklas Hed, Jarno Väkeväinen and Kim Dikert, won a game development competition and used the win to start a small studio called Relude. Two years later, after bringing in its first angel investor, the company renamed itself Rovio, the Finnish word for “bonfire.”

For the next several years, Rovio did what a lot of small creative businesses do to survive: it worked for other people. It built game after game for larger publishers, including big names like Electronic Arts, on early mobile phones. The work paid the bills, but the games belonged to someone else, and so did most of the upside. By 2009, Rovio had made 51 games. It was also running out of money. The team was small, and the company had the funds to make roughly one more game of its own.

So it chose carefully. The team had a long list of possible game ideas and a set of criteria for picking one. Then designer Jaakko Iisalo showed a sketch of round, wingless birds with angry eyebrows, charging at structures. Nobody was quite sure what the gameplay would be. But the characters were so appealing that the team set aside its own selection rules and went with them.

The game took about eight months to build. Angry Birds launched on the iPhone in December 2009. In February 2010, it became the top-selling paid app in Apple’s UK App Store, and a few weeks later it reached number one in the U.S., where it stayed for months. By the end of 2010, Rovio announced 50 million downloads. A studio that had been close to closing became one of the best-known names in mobile games.

It’s easy to call Angry Birds an overnight hit. It came after six years and 51 games. Every one of those games taught the team something about building for small screens, simple controls and short play sessions. The client work wasn’t a detour from the breakthrough. It was the training for it.