About the getKey stuff, I think if ("space".equals(Greenfoot.getKey()) is best, because the thing you check on is never null and is capable of being compared to something that is null. And I think if (Greenfoot.getKey() == "space") compares the pointers, because the 2 Strings are instances, not data types like integers, so this will always return false. But I may be wrong, because I can't run the scenario on this device and therefore don't know if it will work :)

I agree with FRUP, and I would also change the image of the speaker when you click on it: to get a little more feedback whether the sound is on or off.

I think you've got the problem where the edges of the camera cannot go out of the world. So if you move to the left, it will stop when it's at 150 x. The same for the other directions.

And it may be more realistic to stop rendering the sprite/tree altogether once it's too close, instead of showing it cut up in 2 pieces. And btw, awsome update!