To access the Egyptian level, beat all levels in 00 Agent mode. To access the Aztec level, beat all levels in Secret Agent mode.
After you beat every level (including the hidden Aztec and Egyptian stages) on the "00 Agent" difficulty setting, a special "007 Mode" opens up. The 007 mode is a level editor where you can configure options such as enemy health, reaction time, accuracy, and more.
In the train, when you reach the last car, stand on the right side so that Ourumov is directly in front of Xenia. Shoot Ourumov and then keep shooting after he falls and try to hit Xenia. If you hit her, she will say, "Wait for me Alec, I'm hit." You'll be given more time to shoot the floor panel as Alec won't tell say you have one minute for some time. This will also give Natalya more time to find Boris if you're in Secret Agent or 00 Agent Mode.
Also in the train, kill everybody in the first car. Walk towards the brake levers and you'll find two crates. Shoot them to reveal an RC-P90 or DD4.
In the facility, if you don't blow up the all the gas tanks with your mines, then you can use another weapon to blow them up.
At the facility, shoot a scientist in the arm or foot. He will take out a DD4 and start shooting at you. Dodge the bullets and he'll attempt to throw a grenade at you. Kill him and you can now pick up his weapons.
To fight with a paintbrush, go to multi-player mode and select snioer rifle as the weapons. Play any level and pick up the sniper rifle only without picking up ammo for any other gun. Switch to the sniper rifle and push A twice and you will get the Paint brush.
If you play in the Bunker on multi-player mode, go outside and follow the trail to the left. There will be a black wall that if you throw a mine at it, the mine will fall and never stop.
To get even more characters in multiplayer mode (like the game designers, bike rider, and the terrorist) follow the directions below. You can do this code anywhere, but it's best to do it on the Multi-Player Character Select screen while looking at the last available character (Mishkin or Moonraker Elite.) 1. Hold L + R and press C-Left. 2. Hold L and press C-Up. 3. Hold L + R and press LEFT on the Control Pad (not the analog stick.) 4. Hold L and press RIGHT on the Control Pad. 5. Hold R and press DOWN on the Control Pad. 6. Hold L + R and press C-Left. 7. Hold L and press C-Up. 8. Hold L + R and press RIGHT on the Control Pad. 9. Hold L + R and press C-Down. 10. Hold L and press DOWN on the Control Pad.
You'll have to reenter this code if you turn off the game.