NightMare is a scareware program distributed on the Fish Disks for the Amiga computer (Fish #448). It is generally credited to be the first scareware program of its type.[1]
The program was developed by Patrick Evans (Nobleton, Ontario, Canada) in 1990 and was free to redistribute, with source code available from the author.[2]
When NightMare executes, it runs in the background. Every five minutes, it changes the entire screen of the computer for four fifths of a second to an image of a skull with blood on its teeth and a bullet hole with blood leaking out of it, and plays an echoing shriek on the audio channels.[3]