Bart Decrem is transforming the way we play music?with a twist on play. He's the CEO of Tapulous, a small iPhone gaming company that released the rhythm game "Tap Tap Revenge" in 2008. Within two weeks of its release, more than 1 million users were tap-tapping along to tunes by unknown bands (indie friends of Tapulous developers) and, soon enough, big names such as Coldplay and Dave Matthews Band. Seven titles later, including "Lady Gaga Revenge," the TTR family is the App Store's most popular series, boasting more than 25 million downloads, 600 million games played and $1 million in monthly sales in 2009. Mr. Decrem has said TTR's continued growth stemmed from his company's embrace of in-app downloads, a recent App Store feature that allows players to purchase additional goodies without leaving the app interface.

In early February, Tapulous launched its latest iPhone series, "Riddim Ribbon," a hybrid racing and rhythm game?think Daytona USA meets "Dance Dance Revolution." The debut reached No. 1 in top-grossing games in three days.

See the rest of the 2010 Creativity 50 here.