Perhaps it should be explained that stars are earned by killing the heavily armored turret-like bases that are positioned on the ground. This can be done by using a Nuke, or by firing a fair amount of bullets at them.
@Janto, keep that ass from which you talk through shut. With He-Man or whatever as your profile pic, I'm pretty sure you can't be a liable source of comments, or anything for that matter. nerdook, this is another awesome game. Can't wait for updates!
Some Tips: Be sure to call in your best units first; they may require a higher respawn cost, but an early advantage is crucial. Always go for +1 Reinforcements point when available. Without those points, it's substantially more difficult to win battles.