Unlock BFG To access the BFG enter the following code: FG6S-WFZG-7MDP-PZGT.
City Streets level-Unlock BFG (M249 Machine Gun): Enter any of the following codes as your 'Profile' name making sure you also enter the dashes. When the code is done click 'Done' and you'll be able to enter your real profile name. If you have entered the code correctly When you begin the first level you'll have an M249 machine gun instead of your normal gun.
Unlock Silver Weapons (unlimited ammo): On Normal or Hard difficulty level beat the game
Unlock Black Ops Mode: On Hard difficulty level beat the game
Unlock BFG: When creating a Profile enter 5SQQ-STHA-ZFFV-7XEV as your name and then press 'Done'. You will then be returned to the 'Profile Name' screen to enter a real 'Profile' name. When the game starts you will have the BFG.