Holy extra-gameplay Batman! If you live in the UK you can apparently pre-order the nardgasmic Arkham City from Tesco (Tesco does games now?) and you will get a code for an extra four hours of gameplay. FOUR HOURS? Basically with the code you will be able to download something called The Joker’s Carnival Challenge Map. It’s an additional set of missions and challenges set inside Joker’s hideout in Arkham, inside of which you will have to use all the usual stealth, detective work and combat to get through. And as I said it’s estimated to add an extra four hours of gameplay.
I don’t know about any of you, but I’m seriously considering breaking my streak of never ordering anything from Tesco…
MMGaming.net 
I actually had trouble finding the game on the Tesco website. For any of you who also have difficulty, here is the link to buy it: http://bit.ly/p0uSCs