Stronghold simulates castle sieges well enough to recommend it to those who are interested in the premise.
Stronghold is both a real-time combat game that focuses entirely on castle sieges and a village-management simulation in the vein of Zeus or The Settlers. The subject matter alone gives Stronghold a leg up. It's been years since a game let you pour boiling oil on invading hordes, and Stronghold simulates castle sieges well enough to recommend it to those who are interested in the premise. But it's a hesitant recommendation, due to a poor interface and mediocre campaigns.
There are two campaigns, one military and one economic. The economic campaign is made up of a handful of timed missions in which you must acquire a certain target amount of goods or gold. Occasional threats in the form of bandits and animals will require you to maintain a basic militia, but the mission goals are always economic. This campaign only serves to highlight the fact that as a management simulation, the game is pretty shallow. You build woodcutters, farmers, and miners, and the goods are brought to your storehouse. You build secondary producers, who use these goods to produce weapons and food.
You must also ensure you have enough food to keep your people happy and enough gold to hire soldiers. Since taxing your people makes them unhappy, and unhappy people will leave your kingdom, you must also find ways to keep your popularity high. This can be done by providing them with extra food, churches, or alehouses. Keeping your people happy is relatively unchallenging, although it seems complicated in theory. Most of the time, providing more food will be all you need to do, and the rest is unnecessary.
The economic and management elements of Stronghold are simple, but they are just the setup for the military game. The military campaign lets you defend against sieges, and siege other castles, as well as incorporate the economic elements. In the military campaign, you play the son of a king who was betrayed and murdered. His land was divided among four men: The Snake, The Pig, The Rat, and The Wolf. You must take back your father's land piece by piece.
The early stages of the campaign act as a tutorial, and a much better one than the game's actual tutorial option. In the beginning you will have only archers to defend your castles, and that will be all you need. Later, you'll have access to pikemen. Much later, you'll get the more advanced units such as swordsmen, engineers, and macemen. Part of the problem with the campaign is that you are stuck with the lowliest of units for the first half, and then things start to escalate rapidly. Your first castle siege is also your first time using engineers, who make your siege weapons, and the trial-by-fire element comes out of nowhere. Not only have you not had practice using the units, but it will take you some time to learn how to use them.
This suggests one of Stronghold's biggest problems: The interface makes little sense. There is a series of tabs on the bottom of the screen, each of which shows you different types of structures you can build. There's a farm tab, a food-production tab, a weapons-building tab, and so forth. Then there is a castle tab that lets you build walls. To build towers, you need to go to the castle tab and then click on the tower button, which opens the tower screen. Same for gatehouses. Moats are on the gatehouse screen. Or possibly the tower screen. There's no real rhyme or reason for where some things are located. Your barracks and armory are under the castle tab, but weapons manufacturers have their own tab.