Cheat mode
This procedure involves editing a game file; create a backup copy of the file before proceeding. Use a text editor to edit the "eib.ini" file in the "system" folder in the game directory. Look for the "(Engine.GameInfo)" heading, then enter the line "bCheatsEnabled=True" below it. Then, look for the "(Engine.Console)" heading and change the "ConsoleKey=0" line to "ConsoleKey=192". Then, press ~ during game play to display the console window:

Code - Result:

god - God mode
fly - Flight mode
walk - Disable flight and no clipping mode
allweapons - All weapons
ghost - No clipping Mode
allammo - Extra ammunition
invisible [0 or 1] - Togle invisibility
killall - Kils everything
loaded - Get all items
unloaded - Remove all items
loadspmap (map name) - Select map
oldmovie - Old movie mode
summon (item name) - Spawn indicated item
blindai [0 or 1] - Toggle blind AI
deafai [0 or 1] - Toggle deaf AI
blindenemies [0 or 1] - Toggle blind enemies
deafenemies [0 or 1] - Toggle deaf enemies
supersquad - God mode for squad

Note: You must reset the cheats every time you play (i.e., retype everything with the exception of the line "bCheatsEnabled=True").You must move it under "(Engine.Console)" and must re-enter "ConsoleKey=192" in order for the console and the cheats to work properly in the game.

Cheat mode (alternate)
Enter "2ndsquad" as your profile name to unlock all levels, old movie, infinite ammo and supersquad.

Full team health
Die four times after a save point and you will be asked if you want to heal your squad.