I had written this applet a few years back, just to play around with my new-found-knowledge about threads and applets in Java. It is similar to the snake game, though its much simpler and there is no possibility of looping over yourself (its a BALL!)
Pardon the poor code-style; I'm much better now!
To run the applet, either you'll have to use a Web Browser or use appletviewer, like I did. Detailed instructions can be found at: https://sites.google.com/a/eng.ucsd.edu/cse-8b-winter-2014/schedule-and-assignments/psa7/set-up-appletviewer