Along with Kaiser, this game defined the 'ruler-genre' for years to come! The premise is simple: make your country strong and stable inwards to conquer your neighbours.
Fitting the name, Imperator is set in ancient Rome. Your main job is to distribute the budget amongst several groups of interest. Every year, they demand a certain sum and it's up to you whether to comply fully, partly or not at all. That influences this group's stance towards you. If you give your wife (!) only half the amount she wanted, she'll be more likely to start a rebellion. On the other hand, if you provide the merchants with even more money than they said, they'll love you!