A free app for Android, by Prerak Bhatt.

[Substratum] Emoji Changer is a powerful and easy-to-use tool that allows you to change the entire look of your device with a new set of emojis. It allows you to create and customize the appearance of your own device and is compatible with most smartphones and tablets.

This app works in a similar way to other apps, such as the system-wide font changer or the emoji keyboard, but it has a few differences. It works as a theme and can be applied to your entire device, while the other apps are limited to your home screen and/or lock screen.