iPhone application developer EpicTilt is officially in the music-game business, launching a competitor to the hugely popular Tap Tap Revenge. Much like the competing game from rival Tapulous, EpicTilt's TapStar has users matching on-screen prompts to the rhythm of the song a la "Rock Band" or "Guitar Hero."

The TapStar interface looks much like that of the classic "Dance Dance Revolution" in that the on-screen prompts appear as arrows at the four corners of the screen.

The game will launch with licensed music exclusively from Sony Music Entertainment. Eventually, other label content will make its way to the game after Sony's exclusive period ends. Songs will include artist images in the background as the game is played, and it also includes iTunes buy links. With Apple's new iPhone operating system, EpicTilt can also make new songs available to buy from within the game.

EpitTilt is an iPhone game developer that has created several applications for such artists as Asher Roth, Akon, Lady Gaga and others. Getting into the music-specific game space is a natural extension, given the vast popularity of the groundbreaking Tap Tap Revenge. That game was the most popular iPhone game of 2008, with more than 11 million copies downloaded.

At launch, TapStar is 99-cents, but the price is expected to go up in the next few days.