All Weapons
To get All Weapons R2,L2,UP,Down,X,UP,SQUARE,X

Glitches
Kill A UN Guard Glitch
In the Level Motorcade Interception, one of the mission objectives, is to spare the UN guards and not kill hem. You can simply kill them by approaching behind them and use the Fibre Wire on them to kill them. Using only the wire will glitch and allow you to kill them.

Unlockables
Get ThisBy Doing This
Get An M4Earn a Silent Assasin ranking on all of the St. Petersburg
missions up to and including ''Invitation to a Party'' without any aggression. Pass ''Invitation to a Party'' last and you will recieve the M4.
Get a Sawed-Off ShotgunYou will receive the ''Sawed Off Shotgun'' after gaining 'Silent Assassin' ranking for the 2nd time in the
game. This must be on a mission which you haven't received the ranking before.
Getting Silenced BallersYou will receive ''Silenced Ballers'' after
gaining 'Silent Assassin' ranking for the 1st time in the game.

Unlock Sawed-off Shotgun
To unlock the sawed-off, beat any 2 missions with a Silent Assassin ranking.

Punch Mode
While playing, press: R2, L2 Up Down X Up Up.

Full Health
Press R2, L2, Up, Down, X, Up, Down.

Unlock Silenced Ballers
To unlock the Silenced Ballers, get a Silent Assassin ranking on any mission.

Bomb Mode
While playing, press: R2,L2,UP,DOWN,X,UP,L1

Nailgun Mode
To get Nailgun mode, press: R2, L2,UP, Down, X, L1 twice

Level Skip
Press R2, L2, Up, Down, X, L3, O, Triangle, O, Triangle

Codes
Get ThisBy Doing This
God ModeR2, L2, Up, Down, X, R2, L2, R1, L1
Level CheatR2, L2, Up, Down, Square, Triangle, Circle on Main menu
Slow MotionR2, L2, Up, Down, X, Up, L2
Full HealR2, L2, Up, Down, X, Up, Down
Punch ModeR2, L2, Up, Down, X, Up, Up
GravityR2, L2, Up, Down, X, L2, L2
Lethal ChargeR2, L2, Up, Down, X, R1, R1
Bomb ModeR2 ,L2, Up, Down, X, Up, L1
MegaforceR2, L2, Up, Down, X, R2, R2
Nailgun ModeR2, L2, Up, Down, X, L1, L1
All WeaponsR2, L2, Up, Down, X, Up, Square, X
Level CompleteR2, L2, Up, Down, X, L3, Circle, X, Circle, X
Mission SelectQuickly press R2, L2, Up, Down, Square, Triangle,
Circle at the main menu.

Bleeding Chair
Play the mission Basement Killing and shoot the man with a silenced smg in the back sitting in the chair.just for proof pull him out of the chair and drop him somewhere away from the chair and get up close to the again and shoot the chair and the cair will have bloody bullet holes.