We recently ran a story at Gamezebo about a study done by the analytics company App Annie.  It revealed some interesting facts about what makes mobile apps sell.  Today we’ve got another analytics article for you, this one by way of David Meyer at Gigaom, about some interesting stats gleamed from apptrace.com.

Launched by the German company Adeven, Apptrace is a new app tracking website that can be perused by anyone.  Mobile gaming developers and enthusiasts alike can use apptrace.com to follow what’s selling, what’s popular and what’s not.

The site lists daily global rankings of apps worldwide, provides “detailed reports per application,” and is free to use.  Put simply, Apptrace is comprehensive library of apps and how the public interacts with them.  I’ve had a good bit of fun this morning poking around their database.  Did you know that two of the top five grossing iPad titles are slot machine games?  Or that the median price of an iPad game is $1.99, as opposed to $.99 for the iPhone?  Even more interesting is that, according to the Adeven, almost 400,000 apps in the App Store — nearly two-thirds of them — are “zombie” apps.

Not zombie games, mind you.  A slightly more accurate name for these apps might have been “ghost” apps, as what makes these apps zombies is the fact that they exist totally unnoticed to the world.  These 400,000 apps have never been downloaded, do not show up to users when searched for, and are not ranked by Apple.

“The reality is there are only a couple of thousand apps that really make some kind of downloads,” Christian Henschel, Adeven CEO, told Meyers. “This is based on Apple’s closed system — it’s tough to discover those kinds of apps. You don’t have proper search, so the only way to discover new apps is through the top listing.”

While these 400,000 unseen apps aren’t literally zombie apps, I’d guess that the number of zombie themed games in the App Store might be close to that.  I’ll have to hop onto Apptrace to do some research.