Rocksteady is showing their appreciation to all the fans who supported Batman: Arkham City by offering a free skin based on the Dark Knight's appearance in Batman Inc. The free skin can be downloaded from PSN, Xbox LIVE Marketplace, and Games for Windows Marketplace on December 21.
Rocksteady also released a cheat code that allows players to use any Batman skin before completing the campaign. On the main menu (after selecting a save file), press Left, Left, Down, Down, Left, Left, Right, Up, Up, and Down. You'll hear a sound effect if you entered the code correctly.