Unlock All Levels
You can access to every level in the game, even the ones you haven't reached over the course of the game's single-player story mode yet, using a cheat code. The code will also unlock some bonus content, such as extra guns, clips and galleries. To enter the code, go to the Chapter Select screen, hold down the "Select" button on the controller, and then sequentially press "Right," "Right," "Left," "Left," "Square," "Square."
Extra Smoke Grenades
To add 2,000 smoke grenades in your arsenal, which you can use to distract enemies during game-play, you enter the following code while playing the game in any level: press "R1," "Circle," "R2," "L2," "Square." If you entered it correctly, a message should pop up, indicating you have 2,000 smoke grenades. This code works only in single-player mode.
Extra Frag Grenades
Another cheat code will give you 2,000 frag grenades, which you can use to take out enemies at a distance. To enter this code, while playing a game sequentially press "R1," "R1," "L2," "Circle," "Circle," "X." If you entered the code correctly, a message should pop up confirming it. You can use this code only in single-player mode.
Extra Interviews
There are numerous fictional interviews you can unlock that add extra depth to the game and are available from the "Extras" menu, including the interviews of Gordon Boulton, John "Bud" Hawk and Sgt. Stan Markut. To unlock these interviews, simply complete the game's story mode one time through on any difficulty level.