Enter the following as your Profile Name:

BRUTAL         Harder Difficulty 

DBLDAY         Quick Death 

DEADAIM        Better Aim

ERINROBERTS    Better Defense 

HVYMTL         Cartoon Mode 

MATTSOELL      Tougher Characters 

RAPIDFIRE      Rapid Fire Weapons 

SPRAGNT        Stupid AI 

Extra multi-player characters:
Find hidden DNA containers to unlock different characters in multi-player:

Confed Marine: Mission 1 or Mission 6
Feral Colonist: Mission 2
Feral Outcast: Mission 3
Feral Shaman: Mission 9
Fire Hound: Mission 13
Gunthar Ghent: Mission 10
Hunter Lord: Mission 18
McTavish: Mission 14
Militia: Mission 5 or Mission 11
Outcast Shaman: Mission 7
Seer Follower: Mission 4
Seer Priest: Mission 8
Shadoon: Mission 12
Shrike Heavy: Mission 16
Shrike Hound: Mission 17
Shrike Soldier: Mission 15

Bots in multi-player:
Start a game of Squad Deathmatch. Plug in Controller two and set the A.I to "Fire At Will." Grab some good weapons and medkits, then disconnect the controller. Your squad will now be facing three bots in multiplayer mode.

Maximum MK ASLT ammunition:
When you find a duplicate MK ASLT, keep picking it up. It will raise your maximum ammo to 600.

Thanks to Revolution readers paul, Alonnis Brown, SPAS-12 and Markimark!