NightMare was a screamer program developed in 1990 by Patrick Evans, which was distributed on Amiga Fish computer disks. The program's creator made it free to redistribute, and its source code was made publicly available.
When the user executed the code "Nightmare" in the Amiga Disk Operating System (DOS), the screen would quickly display a digital illustration of a skull facing right with its jaws open, its teeth covered in blood, and a bleeding bullet hole in its side, accompanied by a resonant shriek which echoed out. The screamer would repeat every five minutes.
Very little information is available regarding this program, due to how old it is and Amiga discontinuing their line of hardware in 1996. A similar program called McDonalds.exe was developed in China in 1999 to disrupt newer operating systems like Windows 98, followed by more types of scareware applications which emerged in the 2000s and 2010s.
NOTE: The following video contains a screamer!