Beat the game with using Lieutenant Commander difficulty.
Defuse The Bombs
In the third level you must defuse 3 bombs in the alloted time. To make things easier disarm the to bombs close together to the north east. Then kill terrorist leader in building C. This will reset the clock. Then go for the last bomb. By the way each bomb takes a little under 30 seconds to defuse. Good Luck Commander.
Get multiple Grenade launcher
Finish the game 3 times.
Glitch: The Game Online
Find a ladder, when online, climb all the way up the ladder (to the top) then turn 180 degrees and LADDER SLIDE (by pressing circle) AT THE TOP OF THE LADDER. When you have reached the bottom of the ladder by ladder sliding, then turn 180 around and you will not be facing the ladder. BUT you will see a climb option at the bottom of you screen. Press circle and you will climb below the ladder and then when you are on the ladder DON'T CLIMB DOWN! You ladder slide but don't push down on the anolog stick, press CIRCLE.
Lieutenant Commander Difficulty
Beat the game with using Lieutenant difficulty.
Lieutenant Difficulty
Beat the game with using Lieutenant JG difficulty.
Lieutenant JG Difficulty
Beat the game with using Ensign difficulty.
More Weapons & Smarter A.I.
Beat the all 12 missions to get more weapons, i.e Desert Eagle, Uzi, and Grenade Launcher. The enemies will also be smarter and better shots. The more you play through the higher your rank will be, plus more weapons and more intelligent enemies.
Pick level
Beat the game with using Lieutenant JG difficulty.
Rear Admiral Difficulty
Beat the game with using Captain difficulty.
Refill Your Clip Without Reloading
Once you kill somebody and you only have a few bullets in your clip, switch weapons with the guy you just killed and switch back, your clip is full without the cost of one clip.
Special Headset Commands
Say these commands into the headset during gameplay to trigger the corresponding team actions:
"Bravo defuse bomb": Put your crosshairs on the bomb and say this to... you guessed it... defuse the bomb.
"Bravo open door": Same idea. Point crosshairs at door and speak.
"Breech, bang, clear": Point your crosshairs into an open room and your team will throw grenades inside.
"Hands up, get down": Sneak up behind an enemy and yell this, and guess what?
"Team low profile": Your crew will go into stealth mode.
''Hands up, get down:'' Say this to guards to get them to do it.
''Don't ask, don't tell:'' Your teammates will not help you very much.
''Bravo snipe:'' Your teammate will use their sniper rifle.
''Bravo kill me:'' Your team will kill you.
''Bravo report status:'' Your team will tell you their details.
''I got a gun; what do you got?:'' Find out what weapons they have.
Terrorist weapons
Successfully complete the game with a rank of ''Ensign'' to unlock terrorist weapons in the armory in single player mode.