Stronghold Crusader for its time had a fun little Artificial Intelligence. Above all, that was - and still is - defined by a pre-defined castle template that varies per character.
The AI tries to build a castle gradually, where each building has an order (1 being the first one, etc.), so the castle can be built starting with the essential buildings, with the less important ones added later. Some opponents build include a few pauses in their construction, allowing for a more gradual build-up
in Stronghold Crusader & Crusader Extreme