Cheat Codes:
Enter these codes at the password screen.

IAMWOMAN:
Infinite armor

THEBIGBOYS:
Unlimited ammo, fuel, and attempts

SADISSA:
4 attempts

NOSFERAT:
7 attempts

STRANGELUV:
Infinite ammo

EARTHFIRST:
Infinite fuel

ANGRYLOCAL:
People follow you everywhere

GHANDI:
Natives worship your chopper

QUAKER:
World peace (no shooting)

DAVEDITHER:
More powerful weapons

DRBENWAY:
Double damage

MOUNTADEW:
Unlimited fuel

VULTURE:
Double fuel mileage

FUGAZI:
Infinite ammo, infinite fuel, infinite attempts

MIDNIGHOIL:
Infinite ammo, infinite fuel, invincible chopper

Infinite Lives:
For infinite lives, enter any level password, but don't press Start. Instead, press Triangle to clear your entry and then ype "ELVISLIVES". Passwords:

1 -- worstcase
2 -- grandtheft
3 -- grozney
4 -- chernobyl
5 -- civilwar

Power-ups:
On the level where the reactor blows up, destroy all the buildings on the radioactive rivers, and inside some of them there are power-ups, like the super-gun.

Elvis:
Also, if you destroy the big mansion, then elvis comes out and goes 'uh-huh-huh' when you shoot him.

Take Nick Arnold to the restroom:
On the first level, the second mission is to rescue Nick Arnold. Immediately after this is done, fly to your base and turn left. There should be a co-pilot landing zone and a little shack. The shack is an outhouse. Land there and Nick will use it.

Christmas secret:
Look in the south-eastern corner of the Crimea strike map to find Santa Claus and the reindeer getting ready to depart for the holidays. Shoot the sleigh without hitting Santa or the reindeer to receive an extra life.