Believe it or not, all coding for this scenario is in one World sub-class constructor. The score-counter, time-counter and blue-dot are Actor objects that each control themselves. A later update will reveal the code.

In addition to what FRUP said, the sound needs to be set in a GreenfootSound object reference field: [code]GreenfootSound bgSound = new GreenfootSound(/* name of sound file */);[/code] so it can be referenced later, in order to use the 'stop' method: [code]bgSound.stop();[/code]

Would be nice to have a key for random distribution of 'on' cells. Also, noticed that neighbor counting is somewhat flawed along the edges (could not say why). Place two along an edge and four more extending away from that edge forming a 2 by 3 rectangle of 'on' cells with 2 along the edge. On the next cycle, the inner two should go away and two should appear next to where they were extending away from the middle of the rectangle; but this does not happen.