As indicated - player interaction was the essential target when creating the new expansion, and so one of the new concepts introduced for the City cards is the possibility to force other players to incur debts. Thus, the playing of certain Secret Society City cards will grant their owner some victory points, whereas all other players are forced to lose some money. If they cannot or do not want to discard money, they will have to take a corresponding amount of debt markers, and each debt marker will lead to the loss of a victory point when the game is over! This is quite nasty indeed, and such an effect can also be triggered by building the first stage of the new Petra-wonder which is included with the expansion.

Some other cards like the Consulate or the Embassy deal with "international relations", and in effect these buildings allow a player to declare peace with his neighbours for the age in which the building was built. Thus, the player will receive a Diplomacy marker for this age, and at the end of the age this marker means that the player totally drops from the field of conflicts. So, his military strength will not be compared to the strength values of his neighbours, but instead his neighbours will face each other, just like they were sitting next to each other! This may lead to quite unexpected results, forcing players into a direct conflict who may not have thought that they would ever get into such a situation. The second new wonder - Byzantium - also takes on this theme of Diplomacy markers, and so its ruler will get a new Diplomacy marker whenever he completes a stage of this wonder.

Other interactive card effects are related to the production capacities of neighbouring players, and the so Illegal Landing Places give a discount when purchasing the right to use a resource from the player's left or right neighbour. Yet another kind of City cards bears a mask-symbol, identifying these cards as giving their owner the possibility to spy on his neighbours. For each card with a mask symbol, a research symbol found in a green building of a neighbouring city may be copied!

Apart from these core elements of the new expansion, Antoine Bauza has included a very nice extra, and this are 3 news Guilds and 6 additional Leader cards. The guilds take on the novelties introduced here, granting additional victory points for black City cards or causing once again a loss of coins for all other players. The Leaders on the other hand make the expansion fully compatible with last year's expansion 7 Wonders - Leaders, and so the new expansion blends in perfectly with all other components of the game.

Seasoned players definitely will favour to include both expansions, and indeed using both expansions together seems to be the best way to go, since the players now will feel a considerable broadening of their possibilities, and even some tactical issues need to be considered especially due to the new interactive cards (Will I run out of money at a crucial moment? Will one of my neighbours go for a diplomacy marker?). However, this increase in playing depth comes at a price, and in case of 7 Wonders the inclusion of both expansions means that the game gets a bit harder to learn for a new player. Thus, it seems advisable to play just the basic game a few times if a new player joins in, and then add the expansions on a step-by-step base in order to give the newcomer a feeling for the impact of the new rules and playing elements. However, once these steps have been mastered, the expanded game of 7 Wonders will be even more addictive than just the basic game!