DEMON! is a game of tag played on a screen full of PETSCII obstacles. Every time the player (a circle) catches the "demon" (a different circle), a new opponent will spawn. The game flows quickly, and the demons are hard to catch. The keyboard buffer is the true enemy in this game—your buffered movements will cause you to overshoot your quarry if you aren't careful.

In addition to the keyboard controls, you can use a joystick to play this game. I don't think PET joysticks were common, but they were an option.