Both purchasing music and games has changed dramatically in recent years, thanks to Apple and its iTunes Music and App Stores. So it was an inevitability that someone would try combining the two. The latest album from Björk does just that; she's calling Biophilia the world's first "app album".

Free to download, the app comes with one song, "Cosmogony". Additional tunes are $1.99 each; two have been released thus far, "Crystalline" and "Virus". Unlike the initial song, which simply presents visuals produced by the app's graphics engine in a music video fashion, the others are interactive. "Crystalline" is the most game like of the pair, with the goal being to collect crystals while going down tunnels. Picking them in the requested order will unlock new sections that serve up tricker to nab gems.

"Virus" meanwhile is much like Electroplankton in look and feel. By allowing infected cells to compromise healthy ones, you end up unlocking sounds that can be played around with in instrument mode; the player can thusly create their own songs using the same audio that Björk used to make hers.

In the short times it's been out, there's been a certain degree of controversy surrounding Björk's claim of her effort being the first of it's kind. The Unofficial Apple Weblog points out that an app album for a Swedish artist came out last year, though it appears to lack any of the game-like elements that Biophilia contains.

But if you really want to get technical, folks like Peter Gabriel, Brian Eno, and The Residents have all had similar efforts that predate both, albeit before the age of the iPhone. Anyway, check out Biophilia for yourself via this iTunes link.