A free app for Android, by BSC Studio.

Green Bear Caller Screen is an amazing application for those who want to make their incoming calls even more fun and entertaining. It allows you to choose from various themes, including the one you want. There are various ways to set the theme, such as choosing from the list of available ones, downloading it from the Play Store, or even creating your own. 

This app is a caller screen changer. You can change the screen on your phone or tablet for each call. You can also customize it to your liking. There are various options for the screen, including the theme, the color, the background, and the button style. You can also enable or disable the flashlight.