Hacking is a small mini-game launched by approaching a given machine or remotely, by using the Hack Tool. The first noticeable difference from the first game is that hacking doesn't pause the game. Because of that, you will have to split your attention between the moving needle and enemies, if there are any nearby.
There are four different fields (with various results of stopping the needle on them) through which the needle moves:
No colour - the mini-game will be stopped and you'll receive some damage. It's not very harmful, but you better check out your health after failing a couple times.
Red colour - stops the hack and additionally starts an alarm. If there's a Bot Shutdown panel anywhere near, use it to easily get rid of them.
Green colour - the hack will end in success (which additionally end the alarm started by the machine) or move to the next level.
Blue colour - you also succeed (or move on) and additionally receive a small bonus. Check out the table at the end of the chapter for more info.
The last element worth mentioning is the window with numbers at the bottom of the hack panel. Each time the needle bounces off a wall, the number will lower by one. Once it reaches zero - the hacking will be stopped and you will have to start again from the beginning.
Hacking cameras isn't very complicated. Try to stay undetected (use Electro Bolt in case of emergency) and stand directly under the device. If you cannot reach the camera, just jump. Try not to waste Darts on hacking cameras, it's best to keep them for turrets surrounded by enemies. As the difficulty of the hack probably won't be too high, the camera should be friendly after a couple seconds.
While hacking turrets, make use of the Electro Bolt Plasmid, which will stun the device, giving you time to hack it. Alternatively you can use a Hack Dart but keep in mind that you will probably have to hide from the turret's fire, as hacking doesn't stop it from shooting.
SUCCEEDING WITH A BLUE FIELD
A free First Aid Kit.
The Security Bot will inflict higher damage.
An enemy-triggered alarm will last longer.
Opening the safe will give you additional cash.
Increases the damage done by the turret.
A free random item.