I agree with others that rebels are too vicious and strong, but you may also be if you build an aircraft carrier and a lot of machine gun towers. AI always finds your weakest moment to attack. So getting a healthy economy is hard, but once you reach the modern times era it becomes easy. Just pop a few offices and watch your debt melt and budget grow. Offices are absurdly powerful economy buildlngs which make debts a history. You can also get rich if you produce the right goods but that is much harder because of your uneducated civilians. So if you prioritize the army and then economy buildings, it becomes a joy to run this beautiful simulation. The graphics are the best of the series and game runs smoothly on old systems as well.
