So food is an important resource in the game. how about lets make it even more important? Cities have a hunger meter that is equivalent to your food supplies. Your food is slowly getting eaten away by your city inhabitants. Once all food is gone, some debuffs fall on you. Troops stationed in your city do 20% less damage. You also consume food much faster after leaving the starvation period for a short ammount of time. This could add a whole new level of strategy in this game. Enemies could destroy your food income sources and blockade your city until starvation, then attack your city for an easier kill. Another quest type could come from this too. Towns are starving and need your help supplying them with food.
Another idea I had was disease. It happens once in a blue moon and there are good and bad outcomes. Due to the outbreak, food is rationed, giving you a slower rate of food level deterioration. But, your people are weakened by the disease, giving your troops 10% less health and a 20% longer building build time. Each race has its own way of jumpstarting a disease. Humans could catapult dead cows into the perimeter. Elves could cast a spell (or send in diseased animals). Orcs could unleash a horde of mosquitos.
First suggestion! What do you think?