All of the following cheats require you to hold [Left Shift] down 
and then press the [Numpad - (minus)] button. Then let go and type
the appropriate cheat code (capitalization doesn't matter). 

Nothing is displayed as you type however the key strokes are being
recorded. 				

Code           Result
-----------------------------------
ENDMISSION   - End Mission.
CAMPAIGN     - Unlock All Campaign Missions.
MISSIONS     - Unlock All Single Player Missions.
SAVEGAME     - Save Game.
TOPOGRAPHY   - Generate Map in EMF Format.
GETALLGEAR   - Unlock All Armory Items.
FLUSH        - Flush Video Memory.
FREEZE       - Freeze Game.
CRASH        - Forced Crash Dump.