Escape 3D: The Jail - How did they promote this?

Anyone have a thought on how "Escape 3D: The Jail" has risen on the charts (#4 Free App)? It doesn't seem to have the best ratings. I like the genre, just wonder how they managed to promote it.

LINK: http://itunes.apple.com/us/app/escape-3d-the-jail/id444797596?mt=8

Thanks.