The W.O.I.D. takes place in deep space and you're out to save your sister from evil aliens.
If you have at least Java 1.4 installed just click "Play Now!" in the menu to the left to play the game, and it will be downloaded and automatically run using Java Web Start. The next time you want to play and click the menu option, the game will run directly from your computer and no downloading is necessary. It will start instantly.