Let's add some level design. Go to the right area of the layout and add some blocks. As you can see in the following screenshot, we've placed them with a gap between each other. They will fall down; but sometimes if you start a game with an object too close to another, the collision detection can malfunction.
Try out the game. You will notice that the cannonball does not really have a big impact on the blocks. Select them all and change Density to 0.2
, or you can change it to whatever value you want. This is shown in the following screenshot: