Get an N64 Perfect Dark game, a Transfer Pak, and a Game Boy Color Perfect Dark game. Plug the Transfer Pak into the back of your controller, put the GBC game in the Transfer Pak's slot, and turn the N64's power ON. You will now have the following cheats:

These will change the ally (and its weapon) on Co-Op IF it is a simulant.

The Combat Simulator has several Game Presets (modes that have already been created by Rare) that are available from the beginning, but some of the best you must unlock by beating a certain amount of Challenges. Which challenges you beat doesn't really matter, as long as you have the set total needed to unlock the Preset. Of course, you can alter these Presets just to how you like them :)

Upon going to Combat Simulator from the main menu, select Challenges. Perfect Dark has a total of 30 challenges, and upon beating them you will unlock certain items/areas for the Combat Simulator (multiplayer mode). In order to unlock all the arenas in the Combat Simulator, you must beat a certain number of challenges (which challenges you beat doesn't really matter).

Go to Carrington village:Hostage one and make your way down to the wine cellar. Shoot every single bottle and Carrington will say "Act your age, Joanna."

Can't find a use for combat knives because they're too slow or innacurate? After you kill someone in multiplayer throw a poison knife at their dead body (shouldnt have problems hitting a dead target) when they come back to life, they will start getting poisoned and dizzy once almost to the point of death.

In the area 51 level while you are in the hangar, if you activate both the inner and outer doors before elvis explains the UFO can only hold 2 people, then you can skip the hoverbike area and end the level.

All that is needed are 2 controllers, (3 or 4 if you want the remaining stars), and a simple scenario.

First, plug the 2 controllers in and head to Combat Simulator with a simple scenario saved (such as 1 MeatSim, Kill Limit 1). Take the 2nd controller, head down to ''load game'' and highlight what you will (in the future) use for your Challenge. Take your 1st Controller, and pick a difficult Challenge, such as Challenge 30, and select it until it says ''START CHALLENGE'' (the background will be red at this time). Pick up your 2nd controller, load your simple game, and start your Challenge.

What you just did was fool the game into thinking you're playing the Challenge, but you're actually playing a homemade scenario! Kill the MeatSim, and it's a game won. You will gain the star for the Challenge, and it's rewards gained from beating it.

In the Carrington Institute, go downstairs into the main warehouse and you will see a hover crate. Take this hover crate up the ramps to the office floor and into the targetting range. Take it into the range itself and put it between the doors to prevent them from closing. You can shoot the man outside with any weapon you select in the range, and he will never die. Inspect his body afterwards to find him covered in red spots, knives sticking out of him, and crossbow bolts embedded in him.

Simply set up a multiplayer game against all Dark Sims with nothing but Remote Mines for weapons. It will only take a few seconds for the melee to begin, and you'll soon notice that Sims in Perfect Dark cannot detonate their own Remote Mines after they plant them!

Have a, um, er... blast. The only way you can possibly lose is if you blow yourself up on purpose, and this works wonders in inflating the stats on your bio.

As everyone who has ever failed in this level knows, if the crate you're lugging around gets blown up by stray gunfire, you fail the level due to not being able to access the research section.

Thankfully there's a nice glitch that allows you to bypass having to lug around that annoying crate altogether. The enemies in this area wield Dragons as their weapons, which is the key to the entire thing. Blast your way through the level until you're at the section of the wall that you need to blow up, then access the secondary function of the Dragon -- Proximity Mine -- and place it at the base of the wall. All you need to do from there is stand back and shoot the Dragon so blow both it and the wall up.

You've just accessed the research section without using the crate of explosives, and this glitch works even if you blow the crate up first despite the game telling you that it's a mission failure.

At the end of the Pelagic 2 level after completing most of your objectives and finding Elvis, you're supposed to go through a massive corridor filled with guards hiding behind crates and such. Doing so is a massive struggle, especially on harder difficulty settings.

Thankfully, you have the X-Ray Scanner and can use it to bypass the entire process. Remember the large room on the top floor where you have to activate the Moon Pool Lift? Rather than going through the entire level and opening the door in the manner you're supposed to, slap on the X-Ray Scanner and activate the computer from through the wall.

If you've met up with Elvis at this point, the mission is over. If not, you need to run downstairs and fight your way through the guards until you reach Elvis. From there, return to your shortcut and to the Moon Pool Lift to end the level.

Regardless, you get to bypass the hallways of death at the end of the level, which is what this glitch is used for in the first place.

A little fun for the Air Force One level;

When you meet the President and talk to him, pull out your gun. Then when the Cutscene starts immediatly skip it and kill the President. You'll get a "Objective: 1 Complete" message.