As the name suggests, Knights and Merchants does not focus exclusively on the fighting side of real-time strategy games, but also the building of a medieval economy in order to sustain a military - and the civilisation as a whole - function. This gives it a much greater sense of realism than other similar games given that things such as the amount of people your food supply can sustain must be taken into account.
Controls and gameplay are simple. You can use the mouse for most things in the game. Mostly this is achieved by left-clicking, although to select units the mouse uses more of a "click and drag" method similar to other games such as Age of Empires.
The game also has a "training" level before throwing you straight into a scenario that teaches the mechanics of the game and is useful for people unfamiliar with the way the economy works in this game.
Logistics is 90% of the Business of War
One of the key elements of Knights and Merchants is working for your resources. Many types of real-time strategy games tend to simplify this, whereas this process is often broken down into several stages in Knights and Merchants. For instance, to obtain food, you need a farm. What the farm produces will then be taken to a mill, which will then end up in a bakery - and the end result will be a single loaf of bread. Resources are ferried around between the relevant buildings by serfs, who perform many key functions in this game such as taking food to the military - the game will not automatically do so.
As well as keeping the military fed, you must also keep them armed. In Knights and Merchants, the player also makes their own weapons. For instance, a lumberjack will cut wood which will later become bows by means of the carpenter. The player is also allowed to specify what it is the people who may perform multiple functions should be working on.
Real Estate as a Limited Resource
Because every single unit requires food, and farms and vineyard take up considerable amounts of space. Real Estate becomes the limiting factor to the sizes of army and economy. Most of the game play is spent on Sim City like building and planning of production facilities.
While Knights & Merchants featured innovative formation combat at the time, it also relies too much on simple Rock, Paper, Scissors dynamics and efficiently lethal ranged units. Mechanics of army food supply also allowed to avoid combat, and draw the hungry enemy out of the reach of food carrying serfs forcing them to starve in futile pursuit of the enemy.
Historical Inspirations and Legacy
Knights and Merchants followed in the footsteps of the popularity of The Settlers as a cute management sim by introducing more intricate combat of pikeman, archers and cavalry which could be aligned in 8 directions and moved and commanded in formations as well as a management, city building sim that simulated and neatly displayed every single link in any production chain for every single in-game item, without having to rely on graphs, statistics or spread sheets.