Happy Christmas - Happy 2019 is a wallpaper live app developed by Anemoi Apps for Android devices. It falls under the category of personalization and offers a range of Christmas backgrounds with snow moving. The app has a unique feature that allows you to move your device to move the snow to the sides, which adds an interactive element to the wallpaper.

The process to set the wallpaper is simple. You can tap on the wallpaper for a few seconds and select 'Wallpaper' or 'Set wallpaper' from the options available. You may also define the home screen and lock on some devices (Tablet). The app supports animated or moving screens, and you can select the Christmas theme from the options available. Happy Christmas - Happy 2019 is optimized for Samsung Galaxy and Z line devices.

Overall, Happy Christmas - Happy 2019 is a great app for those who want to add a festive touch to their Android devices. The app offers several Christmas backgrounds with moving snow, and the interactive feature makes it unique.