Cheatmode
To enable cheats,  find "config.cfg" file in the game install directory, open it with 
text editor (example: Notepad) and add the following line:

KEY "cheats" BOOL TRUE 

Note: In order to generate the config.cfg file, you must run, and save your settings 
with the configuration tool. If this is not done, this file will not exist.

Save the changes, start the game and enter the following cheats in the console 
window (press [Shift]+[~] to bring it up): 

godmode - will stop teh squad dying by the looks of it but they will still ned sickbay 
to heal for a while when back at base it seems

quickvictory - will instanly make you win the mission how ever dont try it on 
missions like Area51 as you wont get any items or object back which are needed 
for research similarly on a shot down UFO , u get no UFO hull so no research for 
UFO access. 

quicklose - similar to quickvictory but u lose the mission

destroyobj - destroys objects under the cursor, like cars and other objects with 
red center circle and four arrow heads 

visibility - shows the current visible area by your squad LOS

hitpoints - how much health out of 100% can see enemy health too. good when 
used with godmode so u can heal at the end with medic to try and reduce the 
number of people needing rest in the base at the end of it 

allplans - shows the path on enemies like your squat paths , enemies are grey
enemies - shows all enemies in area
heights - shows terrain level/height flat or sloping
ids - shows squad position number 1-7 (ids 0-6 ) works on enemies too. 
think max of 7 for squad size ?

unitsashidden - units become see through like ghosts
quickabsolutevictory - win mission with items recovered 

Unknown codes:

flare
firecheat
canparalyse
cancontrol
heapped
door
scenemode
morecellu 
snow
area