If you pre-order Batman: Arkham City from UK supermarket Tesco you'll get a code to unlock the Joker's Carnival Challenge Map.
This is a separate set of missions based inside Joker's hideout. You'll need to use detective work, combat and stealth while inside. It's estimated to add four hours of additional gameplay.
Joker's Carnival Challenge Map is a pre-order bonus exclusive to Tesco in the UK.
Online customers get a code emailed within two business days after their order ships. Store/in-store pickup customers get a code inside the boxed product. All pre-order customers get a steel book edition for no extra charge.
Here's the official blurb on the DLC:
"Are you brave enough to step into the Joker's house of fun? Can you defeat armies of deranged killers in a fight to the finish, hosted by the clown prince of crime in a twisted game show where the only prize is survival?"
A screenshot of the Joker's Carnival Challenge Map lies below.
Tesco recently launched an in-store pre-order facility, which allows customers to reserve their copy of a game and collect it from midnight of launch.
Christian Donlan went hands-on in March for Eurogamer's Batman: Arkham City preview.