Want to show your interest in an upcoming app ? Google now allows Android users to pre-register for an upcoming release. Its a similar practice to pre-registering for a new phone you are interested in assuring that those interested in the handset receive a notification when the device can be reserved with a pre-order.
Glu Media will soon release its Terminator Genisys: Revolution third-party shooter game, and Android users interested in purchasing the app have the opportunity to pre-register for it. Once the game is released, those who pre-registered will receive notification of its availability. If you happen to change your mind before the app is launched, you can also unregister for notifications.
For developers, this gives them a way to measure how much demand there is a for a new app before its release and help developers bring in more money for their newly released app. It is also a great way to remind Android users that an app they were interested in is now live.
source - AndroidCentral