Remove Penalties and Unrestricted Eagle Vision - Unlockable
You would normally face a penalty from guards when you kill certain non-player characters (NPCs). If you complete the game in story mode, all penalties are removed when you play through the memory blocks again. You can kill anyone you want. You will also have the ability to use eagle vision at any time without restrictions.
Escape from Guards - Exploit
This is an easy trick to get away from guards when they are pursuing you. Proceed to the highest roof top you can find and kill the guards that are immediately behind you. After you kill three to five guards, they will give up the pursuit and flee.
Quicker Interrogations - Exploit
When you are in a situation where you need to interrogate a target for information, first execute a quick punch and grab them immediately afterward. Repeat this strategy until the target relents. It will normally take about two grabs to break the target. When you get to the higher levels in the game, you may have to grab them up to five or six times.
Access Vidic's Computer - Easter Egg
Before you begin playing through Memory Block Five, approach Vidic from the rear and tap any key of your choice to acquire his pen. You can use this pin to access Vidic's computer files and his personal e-mail account.