Definitely the best castle sims out there besides
Rampart, the
Stronghold games put you on the leading edge of castle building technology.
Crusader takes you out of Europe and plunges you into the Crusades as a feudal lord fighting your way to victory. Through a series of levels with varying goals, you will raise a thriving community, build fortifications, and fight for your life against the heathens.
The gameplay is split between combat and micro-management. Not only do you have to construct decent enough fortifications, you also have to keep your people happy with what you are doing. A little leeway is given to you here, as you have a few options on how you can keep the masses in line. Religion and liquor will help with your reputation, as will gardens and other leisure areas. You can also use cruelty and fear as the stuff that keeps your castle together. Everything usually has the same effect, but the choices given to you help weed out redundancy.
This level of management can become tedious at times, though, and may turn some players off. You won't find too much quick action here; you're going to have to work hard for it. Most of the early mission goals are to just raise a certain amount of food, while defending off only a handful of weak attackers.
The real selling points for Crusader are the new units. You still take a European role, except now you can hire a whole slew of Arab mercenaries. These new units aren't just European soldiers in Mid-Eastern garb. Peasants, assassins, and mounted archers are just a few of the new additions, and the whole group of them are varied enough that you could construct an entire army out of just these hired goons.
Adding to its depth, Crusader offers a few historical missions, along with a Crusader Campaign, which takes you on a death march through the barbaric desert. Also on the menu are a Free Build mode, where you can construct and maintain the castle of your dreams, and a Multiplayer mode. While the gameplay isn't inherently made for Multiplayer, there is some fun to be had here.