Fortress is an open source game project where you design, build, and defend castles in a medieval setting.
These are some of my thoughts on the project.
Principally the gameplay should be intuitive. You should be able to play the game without really having to read a manual. Controls that are not otherwise obivous should be tooltipped or clearly labelled.
Once entering a realm, it enters a fairly familiar 3D rts scene, where a village or town exists at a key strategic point. Using the townsfolk and an allowance of gold, the player must plan and construct a fortification to fend off enemy advances. Peasants could be the basic unit of the game but not under direct control of the player. They instead must be coerced into carrying out orders, either through payment, loyalty, or force. Depending upon how you rule the land, the people will either love or despise you and therefore react accordingly when you assign tasks. Usually a combination of fear and kindness will be the best route to take. Also a factor will be how the people relate to the ruler that you are loyal to i.e. the Scots will not want to sit nicely under the rule of the English.
Battles should be a more in-depth affair than in Castles. Theere should be many more soldiers viewable and much more chaos. Castle attacks were bloody and spectacular affairs and we should look to reflect this in the game, with thousands of soldiers fighting to the death and many ways in which they meet a gruesome end.
Also things like moats and other defense capabilities need to be in the game. Weapons of war such as seige towers, ladders, battering rams, catapults, and other such equipement all needs properly researching. We nee to pick an era in time and research the weapons that were used in those days and have them in Fortress.
Castle design should be influential on the development of the town around it.
key vocations should be represented in the game - blacksmiths, carpenters, etc.
These people should be hired and fired, but we want to steaer clear of the usual rts trap of gathering reasources and building buildings. People should require wages and leave if they become unhappy enough. Management should be about good leadership, not just mine and build. Gameplay should be about striking a balance between managing the people of your realm and designing a good castle to protect it.