On a planet's surface you'll build an economic infrastructure as well as land-based military units. This economic aspect is another new feature in Star General .
Every planet has several cities, and each can support two installations.
Every unit has a tech level in addition to attack, defense, and all the other attributes you're used to. Each tech center in your empire increases the potential tech level of your units. All other things being equal, if two units are battling it out, the more advanced one is going to win. Unlike other 5-Star games, there are no campaigns in Star General. In an Expansion War, each race starts on a single planet, and then it's every being for itself as they race to grab unoccupied neutral planets, after which they settle down to kill each other off.