AK-47
Complete the "headshots" goal in mission 6-1.
Fall with elevator
Start level 6-2 (Into The Abyss). Kill all the guards in this little area, but make sure not to lose any health. Go through the door directly ahead, then go to the left. Do not kill the civilian. Then go to the right to where the elevator blows and go into the intermission sequence. Run to the platform. Go down the ladder and shoot open the door so that the civilians can get out. Do not get off the elevator. Instead, go to the back right corner and stay there. You will fall with the elevator and lose much of your health. However, you will not be dead and can see through the walls. Note: The only way to exit is to die.
Increased Melee Damage
Only available online. Increases your damage done by melee moves such as kicking and elbowing.
M4 Silenced weapon
Get 10 headshots in Mission 7-1 under the hard difficulty setting to unlock the M4 Silenced in Mission mode.
R1 multi-player rank
Get 70 kills in multi-player mode.
SP-57 weapon
Successfully complete Training Mission 1 with a time less than 1:35. To do this, go halfway through the mission until you reach the point where you must use the night vision goggles to find the code and unlock the door. When you reach this point after crawling through the crawl space, turn right and climb over the crate. Go forward until you fall off, and there will be a crate directly on your right. Climb it and there will be a zip-line. This will take you to the end of the mission.
Unlock Birds Of A Feather
Successfully finish Story mode under the normal or hard difficulty setting.
Unlock FAMAS weapon
Successfully finish the 2nd training mission in single player mode under 3 minutes.
Unlock Goodnight, Sweetheart
Beat all the time limits in all Training missions.
Unlock M1 Super 90 weapon
Destroy 5 DU containers in Mission 4-1 in single player mode.
Unlock M16A2 weapon
Destroy 5 DU containers in Mission 4-2 in single player mode.
Unlock M249 SAW weapon
Successfully finish the KemSynth Tower mission with a time less than 2:45.
Unlock M4 Carbine weapon
Destroy 5 DU containers in Mission 4-3 in single player mode.
Unlock Shot Defender weapon
Finish the Sana Yemen mission with a time less than 3:40.
Unlock SMAW rocket launcher weapon
Shoot all the small warheads in Mission 4-3.
Unlock Trapped In The Hornets Nest
Get all Combat Sharp Shooter patches.
Unlock UNP.45 weapon
Successfully finish training mission three without wasting a shot.
Unlock Up A Column Without A Paddle
Get all Elite Weapons Expert patches.