Firefly Studios' Stronghold Crusader is the standalone expansion pack to the 2001 Stronghold. In Stronghold Crusader, the player can command either Crusaders or Arabs loyal to Saladin.
The four historic campaigns, which serve as training for different gameplay aspects, follow the first three Crusades, in which the player alternates between commanding Crusader and Arabian forces. New to the game are the desert environment, which holds fertile farming land only in small oases, and Arabian troops available from the Mercenary Post, which do not require weapon production, but are either cheap and only useful in numbers, or powerful but double the price of their European counterparts. Depending on the campaign and the player-set options, the Lord unit can either have a Crusader or an Arabian skin, which also reflects on the cursor (sword or saber).
The game introduces and prominently stresses the skirmish mode, where the player can choose a map and fight against several opponents who do not only differ in appearance, but also in competence and play styles. The four dukes from the original Stronghold (The Rat, The Snake, The Pig and The Wolf) make a return, and they are joined by Saladin, The Sultan, The Caliph, and Richard The Lionheart. Three additional adversaries (Emperor Frederick I, King Phillip I and the Sheriff of Nottingham) were distributed separately in exclusive bonus discs in select stores, but are available for free download on the official website and were part of subsequent re-releases of the game, Stronghold Crusader Extreme and Stronghold Crusader HD.
These adversaries are the player's enemy, in various combinations, throughout the Crusader Trail, a series of 50 linked skirmish missions, which are progressively harder, but can be skipped up to 3 times (using the aptly designed chicken icon). Multiplayer with up to 8 players is available via LAN or over the Internet, and plays exactly like the skirmish mode. In both the skirmish mode and multiplayer, all players, including AI opponents, can use Crusader units alongside Arabian ones.
As with the original Stronghold, Stronghold Crusader includes a scenario and map editor, as well as a free build mode (here called Castle Builder).
The Bonus CDs were provided to individual retailers for an incentive to consumers to purchase that specific chain's version. Notable figures Sheriff of Nottingham, King Phillip and Emperor Frederick were provided as detailed AI opponents - along with their unique castles for the player to skirmish with.