New Productions
Cities on ore, wood, and sheep produce one regular and one commodity (coin, paper, and cloth, respectively). The commodities are mainly used to upgrade your civilization level.
Knights
You can buy knights, and move them around on your roads. You can use them to block opponent progress, and even scare the robber away, setting him where you want to, and stealing a resource. They are vital in the Defense of Catan (see Barbarians below).
Civilization Levels
Instead of buying Development Cards, you build up your commerce, trade and science. As you build up your Civ Levels, you have a greater chance at drawing the Development cards, which have been changed and added to, and divided into three categories, one for each Civ area. The dice each player rolls has one white die, one red die, and one special die. The special die has 3 ships, and 1 symbol for each Civ area. If the Civ area and red die match the upgraded level or lower of one of your areas, you get a Development card from that area.
Barbarians
If the ship shows up, the barbarians move 1 step closer. When the barbarians reach Catan, they attack. Every City counts as 1 attack point, and every Knight counts as 1-3 defense points, depending on what level they are. If there are more defense points than attack points, Catan wins, and the player with the most knights in the battle gets a Victory point. If there is not enough Defense, the barbarians win and the player(s) that have the lowest number of activated knights must turn a city into a settlement.
Metropolises
If you reach level five (out of six) in a civilization area, you gain a metropolis, and it is placed on the board straddling one of your cities (not settlements) and worth two VPs. It also protects your city from barbarian burnings (but not the Robber or Saboutage). There are three metropolises, one per civilization area. If an opponent gets to level 6 in the same civilization as an already placed metropolis, then they will steal the metropolis. As there are no further advancements possible, a level six metropolis is unmovable.
City Walls
For the cost of two bricks, you can build a wall around your city, protecting it from the influence of the robber. It will collect resources as usual. Only cities can have walls, so if your city gets demoted to a settlement because of the barbarians, you lose the wall. Each wall also allows you to have two more cards in your hand before you have to discard on a "7". So if you have two walls on two different cities, you don't have to discard unless you have more than eleven cards in your hand. Each player can have up to three city walls.
The Merchant
The merchant is a new piece that gets called onto the board only through the use of the Merchant development cards. When played, you move the merchant token to a tile adjacent to one of your towns (settlement or city) and are granted the ability of a 2:1 port for that resource until the merchant is again moved.
Additionally, the Merchant is worth one victory point while it remains in your possession. The fact that there are several Merchant cards in the decks mean this is a fluid point that can easily be stolen. Many players save the Merchant until their final play.
This game is also more intense than the original and there are many more chances to "attack" each other due to the power of the new development cards that are added to the game. Game is played to 12 VPs.