Construct buildings and train units as you defend your castle in Iron Overlord. Hire miners to gather gold, which will allow you to purchase constructions. Only barracks are available to you at the start of the game, but you will unlock new buildings as you progress through the missions. Once a building is purchased, you can use it to produce units that will attack opposing troops. Figure out the best strategy to win each battle. Doing so will give you skill points, which you can spend on unit upgrades.