Warrior Kings is a 3D Real-Time Strategy Game similar to Shogun: Total War. Set in a medieval kingdom scenario.
You take control of a brave people and its huge army and have to set up supply buildings, maintain your army and fight large battles against other armies. The game's controls are intuitive and easy to learn, so you can quickly follow the well written campaigns, which are constantly increasing in size and difficulty.
The most interesting features are the possibility to put up an espionage network, lay ambushes, enter diplomatic conversations, make raids or siege the opponent's cities.
Official Webpage (Mac) (The official product page for the Mac version of Warrior Kings on the publisher's website, which provides a profile of the game, a trailer, an overview of the core gameplay, a demo, and ordering information, among other such things.)
The Road Less Travelled (An Apple Games article about the Macintosh version of Warrior Kings, with commentary being provided by Designer Charlie Bewsher (August, 2003).)