PlanetInAction.com has released the first version of a free simulation game that uses nothing else but Google Earth plugin as an engine. The game "Ships" allows you to control different types of ships. The game is three-dimensional, you can travel around the world, sound and visual effects are added.
Ships uses Google Earth API, Flash 8.0, and Javascript. ')
You can play here - ships.planetinaction.com All you need is to install the Google Earth plugin.