Successfully complete the indicated task to unlock the corresponding 
cheat:

Alien (Co-op Buddy): Successfully complete Attack Ship: Covert
Assault on the Special Agent difficulty in under 5:17.
All Guns in Solo: Have a saved game file from /Perfect Dark
Zero/. Alternately, successfully complete Skedar Ruins: Battle
Shrine on the Perfect Agent difficulty in under 5:31.
Classic Sight: Successfully complete dataDyne Central: Defection
on the Agent difficulty.
Cloaking Device: Have a saved game file from /Perfect Dark Zero/.
Alternately, successfully complete G5 Building: Reconnaissance on
the Agent difficulty in under 1:30.
DK Mode (everyone has big arms and heads): Successfully complete
Chicago: Stealth on the Agent difficulty.
Enemy Rockets: Successfully complete Pelagic II: Exploration on
the Agent difficulty.
Enemy Shields: Successfully complete Carrington Institute: Defense
on the Agent difficulty.
Farsight XR-20: Successfully complete Deep Sea: Nullify Threat on
the Perfect Agent difficulty in under 7:27.
Hit and Run (Co-op Buddy): Successfully complete Carrington Villa:
Hostage One on the Special Agent difficulty in under 2:30.
Hotshot (Co-op Buddy): Successfully complete Area 51: Infiltration
on the Special Agent difficulty in under 5:00.
Hurricane Fists: Have a saved game file from /Perfect Dark Zero/.
Alternately, successfully complete dataDyne Central: Extraction on
the Agent difficulty in under 2:03.
Invincible: Successfully complete Area 51: Escape on the Agent
difficulty in under 3:50.
Jo Shield: Successfully complete Deep Sea: Nullify Threat on the
Agent difficulty.
Laptop Gun: Successfully complete Air Force One: Anti-Terrorism on
the Agent difficulty.
Marquis of Queensbury Rules (Enemies Don't Have Guns):
Successfully complete dataDyne Central: Defection on the Special
Agent difficulty in under 1:30.
Perfect Darkness: Successfully complete Crash Site: Confrontation
on the Agent difficulty.
Phoenix: Successfully complete Attack Ship: Covert Assault on
the Agent difficulty.
Play as Elvis: Successfully complete Area 51: Rescue on the
Perfect Agent difficulty in under 7:59.
Psychosis Gun (Makes enemies attack other enemies): Successfully
complete Chicago: Stealth on the Perfect Agent difficulty in under
2:00.
Pugilist (Co-op Buddy): Successfully complete dataDyne Research:
Investigation on the Perfect Agent difficulty in under 6:30.
R-Tracker/Weapon Cache Locations: Successfully complete Skedar
Ruins: Battle Shrine on the Agent difficulty.
Rocket Launcher: Successfully complete dataDyne Central:
Extraction on the Agent difficulty.
Slo-mo Single Player: Successfully complete dataDyne Research:
Investigation on the Agent difficulty.
Small Characters: Successfully complete Area 51: Infiltration on
the Agent difficulty.
Small Jo: Successfully complete G5 Building: Reconnaissance on the
Agent difficulty.
Sniper Rifle: Successfully complete Carrington Villa: Hostage One
on the Agent difficulty.
Super Dragon: Successfully complete Area 51: Escape on the Agent
difficulty.
Super Shield: Successfully complete Carrington Institute: Defense
on the Agent difficulty in under 1:45.
Team Heads Only: Successfully complete Air Base: Espionage on the
Agent difficulty.
Trent's Magnum: Successfully complete Crash Site: Confrontation on
the Agent difficulty in under 2:50.
Unlimited Ammo: Successfully complete Pelagic II: Exploration on
the Special Agent difficulty in under 7:07.
Unlimited Ammo - Laptop Sentry Gun: Successfully complete Air
Force One: Anti-Terrorism on the Perfect Agent difficulty in under
3:55.
Unlimited Ammo - No Reloads: Successfully complete Air Base:
Espionage on the Special Agent difficulty in under 3:11.
Velvet Dark (Co-op Buddy): Start the game.
Weapons Stash Locator: Have a saved game file from /Perfect Dark
Zero/.
X-Ray Scanner: Successfully complete Area 51: Rescue on the Agent
difficulty.