Mobile phone games are becoming a big industry for programmers at gaming companies both large and small.
With smart phones like the iPhone and BlackBerry leading the pack, a range of free and for-purchase games are transforming the devices from simple telephones to interactive experiences.
Gaming publisher Sega, for example, has been creating mobile games since 2002. But technology commentator Mario Armstrong says that while Sega and Electronic Arts are creating games specifically for mobile devices, most games out there aren't from the big companies.
"What really has shifted where when you talk about downloading games and who's making money — when you look at the Top 25 of paid games that are on the [iTunes] Application store — out of all of those, there's only one or two that come from big publishers. Everything else comes from independents or lesser-known video game makers," Armstrong says.
Other big high-tech gaming companies such as Nintendo and Microsoft aren't paying much attention to this new gaming industry.
One of the ways companies can make money with these mobile games is through "micropayments," where small payments are required to unlock levels or open up new features of the game. This business model for mobile devices hasn't taken off in the U.S., but Armstrong says it has shown promise in Asian mobile device markets.