There are alternate Skins in Arkham City, allowing players to change the looks of Batman and Robin.
1970s Batman
AU: Preorder at EB Games
UK: Preorder at ShopTo
US: Preorder at Toys 'R' Us
Animated Series
AU: Preorder at JB HiFi
NZ: Preorder at MightyApe
Batman Beyond
AU: Preorder at Game
UK: Preorder at GameStop
NZ: Preorder at MightyApe
The Dark Knight Returns
Comes with the Collector's Edition of Arkham City
Earth One
AU: Preorder at JB HiFi
NZ: Preorder at MightyApe
Sinestro Corps Skin (PS3 Exclusive)
Buy a Copy of Green Lantern on Blu-ray from Best Buy.
Red Robin
UK: Preorder at GAME OR gamestation,
US: Preorder at Best Buy
New Game :
Complete Batman: Arkham City on Normal or Hard difficulty to unlock New Game + Mode where you will retain all of your gadgets and XP. Several things are different in the New Game +:
No counter icons on thugs.
Different Thug Levels: Tougher thugs are available from the start of the game.
Different Thug Configuration.
Increased Difficulty Bosses: Bosses will be even more cunning
Alternate Ending:
In order to unlock the alternate ending, you must have the Catwoman DLC. In her third mission when you have the option to go left or right with the "loot," head right for the alternate ending. Don't worry; you'll be able to "rewind" back and not ruin anything in the main game.