So far we saw Civilization 5's new Trade Routes system, most of the new civilizations, and the new Social Policies and Ideologies.
Brave New World will ultimately make a cultural victory viable, in turn making the later parts of matches focused on many other things besides military operations.
With diplomacy in Civilization 5, players will need to build relationships with both real player and the computers. With the introduction of the World Congress, you can select Resolutions to change how the world operates. What to suck the militaristic civilization's bank dry? Employ a Standing Army Tax. Want to cripple the civilizations barely grasping on happiness? Ban Luxury resource benefits. No access to Uranium? Then impose a nuclear restriction to prevent nuclear war. The late game no longer forces players to war; players will also fight internal problems.
In order to employ these Resolutions, players gain Delegates from city state alliances, religion spreading and Ideologies; increasing the chances that you will choose the Resolutions. Continue to build these relationships and later achieve a diplomatic victory through selecting a World Leader in the World Congress.
The Civilization 5: Brave New World expansion will release on July 9th for $29.99.