Here are some sites where you can download versions of Blast Thru and its parent Breakout:

Blast Thru - v1.11 (10 levels) and other Blast games

Breakout -the original, playable online

Drew Barrymore Breakout - like Drew? Not when you've finished this game.

Smiley's Breakout - cute 3D graphics

Breakout Clones - more clones