Here's a single Civilization V screenshot which may or may not be an April fool, make you're own mind up as I'm not getting involved. It apparently shows off 'Extreme Diplomacy' mode, looks more like Super Street Fighter Civ edition.

Should normal diplomacy or military might fail to resolve conflicts between empires, Extreme Diplomacywould allow two world leaders to enter a death match and fight to the finish, using special attacks and finishing moves. Two world leaders enter; one world leader leaves. The victor will obtain complete control of the challenger’s world empire.

A deluxe edition of Sid Meier’s Civilization V will include an optional eight-button joystick to bring the classic fighting arcade game feel to these Extreme Diplomacybattles. Additionally, each world leader will have unique special attacks and finishing moves, including:

• George Washington’s Wooden Tooth Chomp Attack
• Otto von Bismarck’s Hurricane Helmet Spike Attack
• Cleopatra’s Phalanx of the Leopard Army
• Genghis Khan’s Arrow Shower from the Mongol Bow
• Julius Caesar’s Reverse Assassination

In addition to the introduction of hexagon tiles allowing for deeper strategy, more realistic gameplay and stunning organic landscapes for players to explore as they expand their empire, Extreme Diplomacygives Sid Meier’s Civilization V players yet another way to take over empires and conquer the world.