Trapball is an arcade style, low-resolution, game that was published on one of the magnazines from the 1980's (T&D Software). In it, you have a central chamber that spews a ball forth, and you have to hit the ball with your paddle before it goes off the edge of the screen.
Title: Trapball
Author: ???
Publisher: T&D Software, Issue #27
Released: September 1984
Requires: Color Computer 1,2,3, 16K RAM, tape or disk, joystick.