Java applets are now blocked in all web browsers. However, you can still run this 'SpaceRocks' game (if your computer has Java installed) by running this command (from a command prompt):
  java sun.applet.AppletViewer https://www.duckware.com/spacerocks/index.html
After running, click inside the game (to give it focus) -- then the keyboard will work.
Pause/Resume ESC
New Game F2
Fire SPACE
Rotate ship LEFT/RIGHT
Move ship forward UP
Hyperspace DOWN