Gears of War 2 - Cheat Code (XBOX 360)

Tai Kaliso : To unlock Tai Kaliso for use in multiplayer, complete Act 3 in single-player mode on any difficulty.
Skorge : to unlock Skorge for use in multiplayer, complete Act 5 in single-player mode on any difficulty.
RAAM : To unlock RAAM for use in multiplayer, have the “A Dish Best Served Cold” achievement on your hard drive from the original Gears of War.
Lt. Minh Young Kim : To unlock Lt. Minh Young Kim for use in multiplayer, have the “Time to Remember” achievement on your hard drive from the original Gears of War.
Kantus : To unlock Kantus for use in multiplayer, complete Act 2 in single-player mode on any difficulty.
Insane Difficulty :To unlock the Insane Difficulty level, complete the game once through on any difficulty setting previously available.
Flame Grenadier : To unlock the Flame Grenadier for use in multiplayer, complete Act 4 in single-player mode on any difficulty.
Dizzy Wallin : To unlock Dizzy Wallin for use in multiplayer, complete Act 1 in single-player mode on any difficulty.
Anthony Carmine : To unlock Anthony Carmine for use in multiplayer, have any Act 1-related achievements unlocked on your hard drive from the original Gears of War.