No Citizen Kill Penelty
After you beat the game, watch the credits don't skip them. You should then wake up, and be able to walk around and go to previous memories. Well, enter any one of them, and go to the masyaf(out of the castle where you start). You can kill anyone without loosing life. You can go around and assassinate anyone you want.
If you need more help, we've got more Assassins Creed cheats and also check out all of the answers for this game
Comments for this hint