Asteroids

Flashteroids
Online Flash game based on the concept of the arcade classic Asteroids. Collect all the flashing targets that appear in sequence, in as little time as possible. Offers three difficulty levels.
http://www.flashteroids.com/

Graviroids
Asteroids game with gravity. Requires Java.
http://www.crashtestgames.com/graviroids/

Mediaroids
Try to get the most points possible in this online Java game based on the original Asteroids arcade classic.
http://www.medialore.com/games/mediaroids/mediaroids.html