I have also added flying saucers to the game. They move across the screen in a random pattern either shooting at asteroids or the player. There are large and small saucers, and each targets the player with a different probability.
The current iteration of the game is close to what the single player game will be like. I still need to tweak the timing of various things though. I also need to add in either a shield or hyperspace. I'll probably do hyperspace since it is random and more likely to piss players off. It might save you, and it might not.
Anyway, here is the current progress. Go ahead and try it out and give me some feedback.
Download Link: Quadroids 0.3