Blaulicht is a fully adjustable emergency light generator. You can change the light color as well as the frequency of the light, or just use it as a steady flashlight by setting the first interval to 0.0 seconds...
Basically it let your screen flash in the color you selected, in the interval you choosed.
Or just use it as a "mood light" in the color you want.
Please check the laws in your country if it is allowed to use this app in your car at night, to simulate police lights, or similar, for example.
You can save and load configurations.