Tesco has announced an exclusivity deal with Warner which will allow the chain to be the only place in the UK folks can get the Joker’s Carnival Challenge Map DLC when they pre-order Batman: Arkham City. The stand-alone mission adds around four hours to the game, and will be included in the game box via a download code. GameStop also includes the DLC as an exclusive pre-order bonus in the US. Arkham City is slated for October 18 in the US, October 19 in Australia and October 21 in Europe. Thanks, MCV.