On many operating systems Java is deactivated by default, due to security issues against criminal programmers, who try to read information from your computer and infect it for their purpose.

Against these criminals Java has given a security setting to choose trustworthy websites which you can exclude from this restriction, for example because you could sue them by using their Impressum information, in case they'd abuse your confidence.

Office computer networks usually have administrators who can activate Java in the system settings/Java and allow only trustworthy websites to run their java apps on your computer. So please ask your administrator to trust this website "".
If you work on your home computer, you can do this by yourself.

Then you can play with both hands on your pc keyboard similar to playing a real