Perfect Dark Zero

To be able to play this difficulty you or your friend must have finished Agent difficulty. By there, you must know the maps, the weapons and the controls to the game.

You can do it it will just take time, good luck and have a good partner to help you with. This is not so hard and Dark Agent but you must know the map and the missions in game that you will face.

Here are some tips from user wildwest08 :

1. USE PLASMA RIFLE!!! You get it at the end of level 10 so if you don't have it play it on agent and make sure you pick it up and finish the level with it to have it in your inventory. This makes the game a lot easier as it is a one or two shot kill. It also has the ability to make you invisible so you and your partner can run past enemies. The less enemies you shoot at the less damage you will take from trying to kill them. There are a lot of levels you can do by being invisible.

2. Take your time!!! Like JMingles said above there is no time limit so be patient. A lot of times you can shoot an enemy then retreat into cover. They will follow and you can get the easy kill without losing health.

3. If needed use the RCP-90. The secondary feature will highlight enemy targets so you can see them easier. This makes it easier to see where the enemies are at.

4. Last of all there are videos on youtube that you can watch to see how they did it or to see the layout of the level.

You will find all the information you need using this site do get the Walkthrough of this game.

http://pdzvideowalkthroughs.blogspot.com.br/
http://nextgenwalkthroughs.com/systems/xbox360/pdz/index.php

Best of luck !!!