This doesn't actually do anything interesting. Just use the arrow keys to move the crab around. I deliberately avoided adding anything fancy to this, so that it would be easier to see what is going on in the code behind the scenes. Feel free to remix and change the background sprites, or make interesting things happen when you run into the balls.
I built this after a discussion with another user about how to make a scroller using sprites as the "background". I haven't looked at anyone else's code, and probably there are more efficient ways of doing it, but this was my attempt.
