The actual gameplay in Stronghold has little to do with the earlier games in the franchise. Here, instead of building a castle and getting knee-deep into the nitty-gritty of what it was like to live during the Middle Ages, you sign up for three campaigns out of medieval mythology. In the opener, you take on the role of King Arthur, battling against the Saxons for control of Britain. In the others, you play as Siegfried, the German dragon slayer and star of a Wagnerian opera, and Vlad the Impaler, the Transylvanian Turk-killer best known today as the bloody inspiration for Dracula.
But nothing of interest has been done to develop these storylines or settings. Buildings follow the RTS template and feature barracks, armories, granaries, and so forth. Resource gathering goes beyond the usual food, wood, and stone, but it does so by adding an annoying level of micromanagement to what should be a straightforward grind of building armies and attacking the bad guys. A game this simplistic probably shouldn't demand the collection and processing of any resources, as mission objectives always involve straightforward building armies and killing enemies.
All of the soldiers featured in each faction are virtually identical. There is little difference here whether you're fighting on behalf of the evil forces of Dracula or the noble knights of King Arthur. Also, since the units themselves are generic, the gee-whiz factor of getting to play Count Blah and his evil minions in an RTS fades quickly. You get little aside from the same old pikemen, archers, crossbowmen, and swordsmen. There is only so much that a developer can do with a medieval setting, of course, but no effort was made to provide significantly different troops to represent the nationalities and time periods represented. A millennium passed between the King Arthur campaign of the mid-400s and the Vlad campaign of the mid-15th century. You would think that more than the color of the shirts would have changed during that time.