From Skye Publications:
The object of KnockBlock is to clear all of the bricks off of the gameboard. Shoot any of the bricks using the mouse to reveal the character that is behind it. If you match the character that is in front of the shooter with the one behind the brick, then that brick explodes and dissappears. Match all the characters to clear all the bricks and win the game. Sounds simple, doesn't it. Play it's much harder than you think.