La Aventura Del Universo
L'Agrupación Astronómica de Madrid, CosmoCaixa Madrid and the Planetario de Madrid have jointly released an astronomy game using Google Sky. The game has been released as a Google Gadget and uses the Google Earth browser plug-in.
The game itself is in the form of a quiz. Each question is placed in a different part of the universe and after you answer a question you fly through the stars to the next part of the quiz. The questions include YouTube videos and models of the planets (observe Jupiter in the screenshot above).
The game is in Spanish but, if you are interested in astronomy, I think you will enjoy this even if you don't understand the language.