Incredibly easy, mostly.....
GREAT GAME!!!, I find it so easy to beat all the other sectors (except the last one) all you have to do when you want to win (and your willing to wait) is to park a heavy cruiser in front of the asteroid(s) that enemy supply ships are targeting (maybe with a repair ship to) and wait. Other than the fact that the A.I. was pittifully easy to dominate most of the time, this game was win!