Gradually fade-out to black. The argument is the duration of the fade, in seconds. The screen will remain black until a TurnOff message is sent to the script. There is no fade-in, however. A negative argument does the same thing as TurnOff.
You can fake a fade-in with TrapRenderFlash. Trigger the render flash before sending TurnOff to TrapFadeOut and the after-effect of the flash will act as the fade.
This script is ineffective if the Dromed configuration variable no_endgame is set.