Initially called the Nokia Camera, rebranded to Lumia Camera after the Microsoft acquisition, the application, in its Lumia Camera beta stage, has been added to the Windows Phone Store, should you want to join the beta program and check out new features before they hit the public version of the application.
However, you’ll have to rock a Lumia 930/Icon, Lumia 1520, Lumia 640, or Lumia 640XL phone powered by the Denim update, in order to download and install the app. Not to be confused with the Lumia Camera (sans beta) app, this version brings some features and improvements to the users ready to test them out. It is a beta, remember that when you run into any issues.
Source: Windows Phone Store