These demons appeared if you viewed the source code of popular sites that gamers read - actually running as hidden ads in IGN, Daily Motion, Games Radar, WWE, Gamespot and Digg, how cute is that?
But wait, it gets better, if you read them you'll find the link http://hellisnigh.com/ and a bunch of stuff like password5:unbaptized that will help you unlock an "earthly reward", such as posters, wallpapers, and other downloadable goodies.
The ASCII demon ad campaign is still running, check the website's source for more (the passwords are different at each site).
EA Games