This expansion pack lets you add another player to the game, expands map and adds new upgrade mechanic to the game. In City of Steel expansion pack you can join the fight as Hector, legendary hero of Troy. It will also give you opportunity to hunt two new monsters - Satyr and Arachne, get on 3 new quests, upgrade your armies and conquer Troy itself! This pack expands number of possible players to 5 (6 with Lost City expansion pack). —description from the publisher From the Rulebook: City of Steel requires the use of the Atlantis and Poseidon expansions found in the Lost City expansion.