Thanks to the kind Belgo-Mexicans at Repos Production, I've been able to play an advance copy of 7 Wonders: Cities a few times and thought I'd provide an overview of what's included in the box and how it works. (Note: This is not a paid preview for a Kickstarter production. It's not a paid preview at all.)
To start with, Cities is not similar to 7 Wonders: Leaders. That expansion added a new "Age 0" to the game, with players drafting a quartet of leader cards that ideally gave them something of a strategy to carry out over the course of the game: focus on military, science, etc.; build sets of this or that; maintain military dominance; and so on.
Cities instead provides a new color of cards – black – with nine black cards for each of the game's three Ages. At the start of each Age, you randomly choose a number of Cities cards equal to the number of players and shuffle those cards into that Age's deck. Thus, each player starts an Age with eight cards in hand (instead of seven), and players will build/sell/wonderize seven cards during an Age (instead of six). So as with Leaders, Cities tweaks the basic play of 7 Wonders without making the game substantially longer. (Cities also includes four new guild cards for Age III, and these cards are mixed with the other guilds and added to the Age III deck like normal.)
What do the cards in Cities do? I won't go into much detail because as Bauza notes, the cards are still being tweaked and changed. (TricTrac.net posted a video overview of Cities on January 31, for example, and the cards in my playtest copy don't match those precisely; what's more, some cards have been tweaked since then. Every push in one direction brings a reciprocal push in another direction or two.) In general, though, Cities matches the original 7 Wonders mix in that some cards comprise a cycle across the ages – think of the military cards providing 1, 2 or 3 strength across the Ages – while other cards stand on their own. Card cycles in Cities are:
-----• Diplomacy – Each Age includes a card worth X VPs that bears a diplomat symbol. When you play a diplomat, you step out of the conflict for that Age, with your neighbors attacking one another instead of you. If you would have won the conflict, too bad – no points for you! Don't play the diplomat in this situation.
-----• Spies – Each Age includes a spy that lets you copy one science symbol from a neighbor at the end of the game. If you have multiple spies, they must copy symbols from different cards, although they can copy the same symbol. They can be ridiculously powerful if your neighbors allow them to be. In one game, I scored 58 VPs from science – completing Babylon, with the science guild and two spies, along with other science cards to have six of one symbol and two each of the others.
-----• Points and Punishment – Each Age includes a card worth X VPs that forces each other player to discard X coins. For each coin that a player cannot or chooses not to discard, that player receives a punishment token, which dings the player for VPs at the end of the game. The tricky aspect of these cards – along with several other cards that force players to discard money based on, say, how many wonder levels they've completed – is that since Cities cards are added to the decks randomly, you never know how many of them are in the game. How much do you need to hold on to your coins? How many more times will you be hit? You have an "extra" card each Age, so do you just throw that away for money to recover your stash or do you keep your money in the first place so that you can buy resources to build that card?
-----• Artifacts – Each Age includes a card worth VPs, and these cards – as with many other in Cities – have money as part of their cost. Thus, the punishment cards squeeze you when it comes to being able to build these as it doesn't matter how much you produce if you have no money on hand.
-----• Mercenary Military – Each Age includes a military card that provides one more shield than you'd normally find in that Age, but the cards cost money – nothing but money.
In addition to these cycles, each Age has a few standalone cards: one that lets you copy the "leveling-up" abilities of your neighbors, for example, and another that allows you each turn to double one resource that you produce. The Black Market, on the other hand, lets you buy one resource that you can't produce each turn for one coin.
The two wonders included in Cities tie into the cards, with one wonder requiring its owner to pay money to build one or more levels and the other providing one or more diplomat symbols as the levels rise. You're going to be a pacifist, and you're going to like it! What's also interesting about these wonders is they provide brick or stone, which means you can now have games in which two players – possibly neighbors! – produce the same starting resource, which leads to more fights for resources in order to save your precious funds.
While Cities can be played independently from Leaders, Cities includes five leader cards that can be shuffled into the leaders deck should be using both expansions. As you might be able to guess, these cards do things like provide extra points for black cards, money when you play black cards, and a diplomat symbol. In one game I had both the Olympus building (the middle level of which lets you build one card for free each Age) and the leader card that lets you build one black card for free each Age – good times!
As I mentioned earlier, you never know which cards from Cities will be included in each game, but with more players, more of the cards are included, which leads to more punishment, more chances for spying, and so on. Thus, the dynamics of game play with Cities mirrors that of the base game in that the feel of the game varies with more or fewer players, just as it varies based on the wonders in play. The same but different – that's Cities in a nutshell.