GEwar is the first truly interactive game built using Google Earth. The game itself is fairly simple, but should provide some fun entertainment for you.
All you ofcourse need is Google Earth and a web browser.

Google Earth can be downloaded here:
http://earth.google.com/download-earth.html


Getting Started

To get started, go here:
http://www.gewar.net/war/

On that page, click on the text that says "To get started, simply click here!". This will get your account set-up. You will be given some basic items to get started.

Next, it will ask you to "download your custom KML file". There are actually a few KML files that you need to download, which can be found here.

- The first is the city display file. This file shows all of the cities that are used in the game, colored based on who owns them, with their height determined by their value (population).

- The second is the army display file. This file shows the current location of all armies that are not currently inside of a home base or city.

- The third is the home base display file. This file shows the location of all of the home bases.