Even before the game is released they already announced some codes. Here they are....multiplayer fighting sounds interesting!

http://codes.ign.com/ob2/068/016/016325.html

________________________________________
Cheat List
Go into the hacking system, and proceed to the cheats menu. Enter these numeric codes to unlock the corresponding function:
All weapons and max firepower: 0034AFFF
Bonus test level: 13D2C77F
Double movement speed: FF00001A
Enemies do not detect you: 0034AFFF
Enemies do not hear you: FFFFFFF1
Faster Logos flight speed: 7867F443
Infinite ammo: 1DDF2556
Infinite focus: 69E5D9E4
Invisibility: 1DDF2556
Infinite health: 4516DF45
Low gravity: BB013FFF
Multiplayer fighting: D5C55D1E
Silent Mode: FFF0020A
Taxi driving: D5C55D1E
Turbo mode: 7F4DF451
________________________________________