The main goal of the game seemed to be to knock down all the blue cubes (or gems) through various creative means using as few throws as possible.
In addition, the Wii remote even allows the game to calculate how successful to make your throw based on how much force you put into it. It is not just enough to do the throwing motion, you actually have to put some muscle behind it to get a "Strong Throw". Otherwise you'll get a "Weak Throw" and the heavy blocks won't move very much.
I took a picture of my sister playing Boom Blox:
Specifically, there was one game called Teeter-Totter which required you to knock a heavy block onto the balance beam to tilt it and make all the gems fall.
Overall, I was intrigued at how a very simple game of physics could be so much fun to play and yet I was hooked the first time I tried it. Without even really thinking about it, I was applying my knowledge of physics concepts like weight, force, projectile motion, velocity, etc. to help me win the game.