This app makes use of the built-in black and white device feature to provide a blue-light filtered screen without the use of an overlay screen, to help relax your eyes at night and disincentivise phone usage.
Monochromatic needs the Write Secure Settings permission, which is normally unavailable to apps. However, you can grant this permission with the following ADB command:
adb shell pm grant uk.co.richyhbm.monochromatic android.permission.WRITE_SECURE_SETTINGS
