Batman: Arkham City is an action adventure video game released in 2011. It is a game based, of course, on the DC comic 'Batman', and it is the long-awaited sequel to the 2009 game Batman: Arkham Asylum. Batman: Arkham City was voted as the best video game of 2011. It also received many awards including Game of the year and the Best Action Game.
To avoid guard's eye:
If the room is full of guards then it is inadvisable to attack any of them as the others are bound to notice you. Therefore to evade the guard and avoid being noticed keep swinging around the ledges until one of the guard say "I lost him".
Big head mode:
To use the big head mode, remove your cyrographic sequencer and press the RB (R2) and LB (L1) together. Along with pressing the two keys keep rotating your right analog stick till the heads of batman and the enemies start swelling.
Corner cover movement:
For this you must be in the corner cover. After getting in the corner cover throw a remote control Batarang and press LT and RT. Then allow the Batman to catch it.
Then again throw a remote control Batarang and you will notice that your position has changed as compared with one you were in the corner cover.
Instant costume selection:
Press the given keys after you have chosen the save slot in menu: Left, Left, Down, Down, Left, Left, Right, Up, Up, Down.
As soon as you complete this you will get an audio verification. After that you will get an option to choose your favourite skin whenever you resume your game.
Killer croc:
To get the killer croc first you have to defeat Ra's al Ghul. After defeating Ra's al Ghul keep moving in the sewers till you spot a button on a wall. Then with the help of a remote control Batarang press the button.