Atari's first cartridge featuring voice, it was available only through the Fan Club via mail order.
From the manual:
Long ago, the peaceful Land of Quad was invaded by cruel Captors who rounded up all the helpless inhabitants and imprisoned them in cages. The Captors called their prisoners "Runts". And the name has stuck. Now you've come to Quad to rescue the Runts and destroy their Captors with your special weapon: phaser balls.