Tap Tap Revenge is only 1 of 122 games to make internet information provider Comscore's list of the 25 most popular iPhone applications, with a penetration of 32% among Apple app users. This basically means that 32% of iPhone and iPod Touch owners who have used the App Store have purchased Tap Tap Revenge, 5% more than the second place application, Stylem Media's Backgrounds. Venture Beat takes this 32% and multiplies it by Admob's estimate of a 15 million strong Apple mobile user base, determining that Tap Tap Revenge has an install base of nearly 4.8 million users. That's rather insane.

Other games making the list include old favorites like Pac-Man, Hangman, and Soduku, interspersed with newer titles like Lightsaber Unleashed and Touch Hockey FS5.

Behold, marketers - some iPhone numbers you can work with, finally [Venture Beat via Gamasutra]

Tap Tap Dance hit iTunes for $5 today with music from Daft Punk, Justice and Moby and was created in conjunction with EMI.

Mark Johns, one of the engineers behind the game, told me that the game was recreated from the ground up using Open GL in hopes of further expanding the title into something more like a platform.

"The model is similar to the expandable content of Rock Band," he said.

It sounds like the company is still deciding whether they want to release music packs for the existing title or reinvent the game with each new artist, but either way, they hope to change the way people listen to music on their portable.

In its current form Tap Tap has you tapping approaching symbols to the beat of a playing song. But other iterations could change not only the gameplay but the music you're listening to, Johns said.

"Say you have a static song, a song about heartbreak maybe," he said. "You listen to the song and it’s kind of the same experience every time. But when you’re playing the game say there is a heart in the middle of the screen and you have taps coming toward the heart. If you do well, you protect the heart and the song is happy but if you don’t, the heart breaks and the music changes."

Already the company has another game lined up for this Christmas featuing six holiday songs by Weezer. Other band-themed songs are planned for next year.

And Johns hopes that much more innovation can be introduced to the gameplay with future iterations.

Taking a leaf from the Guitar Hero playbook, Tapulous have announced a partnership with industrial rock god Trent Reznor and his one-man-band-with-session-musicians outfit Nine Inch Nails to produce the first themed edition of TTR.

The game will feature lots of NIN-themed visuals and over a dozen tracks to tap along with.

Eat your wizened hearts out, Aerosmith.

NIN Edition of Tap Tap Revenge Brings Licensed Content To Apple’s App Store [Techcrunch]