Planet Buster was sent to me by one member of the dev team and is an amazing game where you have to control the moon and prevent the asteroid to destroy the earth. Read the description on the main page before you start or you might be turning around the earth without knowing what to do.
The game is fast and the gameplay is correct (The way the moon is controlled can be disturbing at the beginning but is ok after few tries).
The game is also here to demonstrate the power of their WebGL Engine they are developing which is under the CC-BY License (means you can use it). Don’t hesitate to try it and send them feedbacks. It looks already really nice and promising.
Go to the official Planet Buster page for game instructions and description.