Perfect Dark Zero - Dark Agent mode

Defeating the final Boss in Mission 13:
When the final Boss jumps to the platform you are standing on, he will lunge at you with his sword. Right before he swings it, dive out of the way. If done correctly, he will trip and fall. Quickly grab his sword from the ground next to him before he gets up and start attacking him with it. Note: The sword can be used to hit three consecutive times by quickly pressing RT3. If he manages to get away, he will summon his sword back to him. After this happens, just wait for him to jump back onto your platform and repeat the process.

Dodging the final Boss' moves in Mission 13:
When the final Boss shoots plasma balls at you, just move out of the way. When he teleports onto your platform and starts running at you with the sword, just dive roll out of the way immediately before he swings the sword. This will save you from taking a lot of damage.

Secret passage in Mission 7:
Before Mission 7, select the demolition kit from the weapons menu. During the mission, after you kill the two brothers go across the bridge towards the rocket. When you get to the rocket, go left and down that road. When you get to the end of the road, there should be two doors one on the left and another on the right. If you try to open them, they will say "secured". If you go on to a ramp that is on the right side of the left door, there will be a crack in the wall. Use the demolition kit to blow up the crack to get into the door.

X-ray goggles and Hawk in Mission 7:
At the beginning of Mission 7, before or after you kill the two brothers, there are four lockers on the right wall of the side of the bridge that you start at. If you are looking directly across the bridge and turn 90 degrees, you will see four lockers on the wall. In one of them is a pair of X-ray goggles. If you look around in the wooden crates on the side that you started on, there should be a new weapon called the Hawk. It is a disk that you can throw and slice people with.

Xbox Live gamer points:
Complete the following achievements to unlock 20 Xbox Live Gamerscore points 1,000 total possible points.

Complete a Co-Op mission under the Dark Agent difficulty setting.
Complete a Solo mission under the Dark Agent difficulty setting.
Get 10 kills using explosives in any multi-player mode.
Capture 10 flags in Capture The Flag mode.
Get 10 headshot kills in any multi-player mode.
Get 10 kills in Killcount mode.
Get 10 kills in Team Killcount mode.
Get 10 Melee kills in any multi-player mode.
Survive 10 minutes in Onlsaught mode.
Infect 10 players in Infection mode.
Survive 10 rounds of Eradication mode.
Get 10 sniper kills in any multi-player mode.
Score 10 points in Territory Gain mode.
Destroy 10K CR of property in Sabotage mode.
Get 100 kills using explosives in any multi-player mode.
Capture 100 flags in Capture The Flag mode.
Get 100 headshot kills in any multi-player mode.
Get 100 kills in Killcount mode.
Get 100 kills in Team Killcount mode.
Get 100 melee kills in any multi-player mode.
Survive for 100 minutes in Onslaught mode.
Infect 100 players in Infection mode.
Survive 100 rounds of Eradication mode.
Get 100 sniper kills in any multi-player mode.
Score 100 points in Territorial Gains mode.
Destroy 100K CR of property in Sabotage mode.
Get 1,000 explosive kills in any multi-player mode.
Get 1,000 headshot kills in any multi-player mode.
Get 1,000 kills in Killcount mode.
Get 1,000 kills in Team Killcount mode.
Get 1,000 melee kills in any multi-player mode.
Infect 1,000 players in Infection mode.
Survive 1,000 rounds of Eradication mode.
Get 1,000 sniper kills in any multi-player mode.
Complete five Co-Op missions under the Dark Agent difficulty setting.
Complete five Solo missions under the Dark Agent difficulty setting.
Complete Co-Op under the Agent difficulty setting.
Complete Co-Op on Secret Agent difficulty setting.
Complete Single Player on Agent difficulty setting.
Complete Single Player under the Dark Agent difficulty setting.
Complete Single Player on Perfect Agent Difficulty.
Complete Single Player on Secret Agent Difficulty.
Complete Co-Op under the Dark Agent difficulty setting.
Complete Co-Op on Perfect Agent Difficulty.
Play 10 Dark-Ops games.
Play 10 Deathmatch games.
Play 100 Dark-Ops games.
Play 100 Deathmatch games.
Play 1,000 Dark-Ops games.
Play 1,000 Deathmatch games.

Flag trick:
In a capture the flag game, have one player get the flag and bring it back to his base to score. Before he scores, have the party leader go to the enemy base and stand on the enemy flag holder the colored circle under where the flag starts and stand over it in a position so he can see the color on every part inside of the circle. Once he is positioned, score the flag and stay there. Every time you score it should say at the bottom, 'enemy flag returned'. After that, the flag will come back out as though you dropped it before you made it to the scoring spot. If you stand there, the flag will score very quickly but you will not be able to tell until the round is over and it shows the scores at the end of the round. If the player on the enemy flag holder dies or moves too far away for any reason, the flag will come back to the enemy base. Founded on Xbox Live by: Teddybear01 and ZeroTitan