Upkeep Cost
Most units and buildings require the player to pay for their upkeep every turn. Depending on the type of unit or building, this upkeep can range from very little to more than a player can afford. Payment will be in Geld, Mana, and/or Population.
If a player ever runs out of the required resource to pay for his empire's upkeep, units will disband and then buildings will be destroyed until the player can afford them.