A gift! A gift, straight from Mr. Sid Meier himself. If you're quick, you might even get a whiff of mothballs and superglue off it. A couple of DLC packs have just been made available for Civ V- the first, the Mongol Civilization Pack, is completely free, and introduces the Mongols as a civilization and Genghis Khan as their leader. The second, Babylon, which introduces Babylonians and their king Nebuchadnezzar II, actually came with the Civ V deluxe edition and will set you back £3. These aren't just cosmetic upgrades, you know. Each civ in Civ V has their own tiny set of unique advantages and exclusive units.
Alec and I saw eye to eye on Civ V, agreeing that it was a beautiful piece of work with sorely lacking AI. For those who find swallowing someone else's opinion distasteful, a gameplay walkthrough can be watched beneath the jump.
Here's my Civilization V tip. If you're neighbours with Gandhi, you don't need to build any defenses, because he's Gandhi. Just leave the guy alone.