[APK for Non-N Devices] You Can Theme Google Keyboard on N Preview with Colors and Images!
If you are running the N Preview 3 on your Nexus device, there is a small yet delightful change that you must check out. You can now theme the default (Google) keyboard, with unlimited options!
To enter the menu, simply head to the Google Keyboard settings, and check out the menu “Theme”. From there you will be able to pick the colors, whether or not to display the key tiles, and also pick up an image (any image!) and tweak the black overlay transparency to ensure you have just the right contrast. There are even Dark and AMOLED themes built in, a great match for Android N’s built-in Dark Mode!
Update: You can download the APK and use it on other devices as well, enjoy! (This is the ARMv8 version, so make sure you are running a compatible phone)