Transport yourself to a time when protecting your possessions meant defending your keep, the most secure part of the castle. Keeps were often called "great towers" because of their imposing structure -- walls over 10 feet thick and 75 feet high. They served various functions, from last resort strongholds during battle to sites of castle dungeons. While there are few remaining keeps still standing today, you can get a small taste of what it was like to build and defend a castle in this game that is simple to learn, yet full of strategy and decision-making elements that will challenge all ages.