Assassin's Creed 2 (english): The crowd and the notoriety system
In Assassin's Creed 2, you have been betrayed by the ruling families of Italy- you will have to learn how to interact and use the ‘common people' or, like we call them in the game, "the underworld”, to get your revenge. So you can generally consider that the crowd is on your side (except of course if you behave too badly!). First, any crowd NPC can help you to hide - just go into a group and press the blend button to enter a crowd and lower your chances of being noticed by guards. The crowd can help you to walk through the city unnoticed but isn't 100% detection-proof as some classes of guards actively search you out even in hiding spots.
We have also added a new "notoriety system”. Your actions in the city will impact your notoriety: break the law one too many times and you will become "wanted” in the city.
The notoriety system monitors your actions and is directly linked to the crowd in the game. The more "commotion” you cause in the city, such as killing innocents, the more notorious you become: people will become more aware of your actions and the authorities will search for you. If you are notorious, you have a much higher chance of being seen by patrolling guards, even if you're trying to blend your way through. There are various ways to decrease your level of notoriety and return to an anonymous state:
•Bribe a Herald
•Get rid of warrant posters with your face on them
You can also use certain groups or "factions” to perform specific actions. More about the factions on the next site.