To enable UFO: 
Aftermath cheats open the file config.cfg (found in the game installation directory) with notepad and add the following line: 

KEY "cheats" BOOL TRUE 

Note: The config.cfg will only be present after you go into the game's setup and then close it by pressing "Ok".

Now during gameplay prss [Shift]+[~] to bring up the console and enter a code from below.

Code - Effect 

hireunit - (On global strategic view) adds a new member to your squad 
finishrd - (On global strategic view) complete current research 
allitems - (On global strategic view) now have all weapons 
destroyobj - Destroys objects under the cursor with red center circle 
quickvictory - Instant win but don't take the items (don't do it on important missions as Area 51) 
cancontrol - Removes all mind control effects on squad 
canparalyse - Removes all paralysing effects on squad 
quicklose - Same as quickvictory but you lose the mission 
enemies - Shows all enemies in area 
ids # - Shows squad position number 1-7 (ids 0-6) 
heights - Shows terrain level/height flat or sloping 
visibility - Shows the current visible area by your squad LOS 
allplans - Shows enemie's squad path and enemies are grey 
godmode - Soldiers will not die but still need sickbay to heal before missions 
unitsashidden - Units become transparent
quickabsolutevictory - Win mission with items recovered 
hitpoints - You can see your health and enemy health in %