For the collisions I use a basic distance calculation between the bullet and the center of the asteroid. If the bullet is within that distance, then I do a point-in-polygon collision test. Pretty simple stuff.
The asteroid shapes are randomly generated at the beginning of the level. There are 20 different shapes for each game, and they are randomly selected for each asteroid.
It would probably take me another day or so to finish a single player asteroids clone. I will likely do that, and then move towards implementing the multiplayer modes. Players will be able to start a game as a server, supply an ip address to connect to as a client, or have a game matched for them.
I have uploaded my current progress. It requires Windows to run. Go ahead and try it out and let me know if there are any issues at this point.
Download Link: Quadroids 0.1