If this game does not open and show an empty large gray square in the window it is because your computer does not have the latest version of the Java2 Runtime Environment (JRE).  The JRE is a rather small package and can be downloaded at http://java.sun.com/j2se/1.4.2/download.html for free.  If you continue to experience a problem even after downloading and installing the JRE for your system then contact [email protected] with a description of the problem.