To use these cheats first press F11 during a mission and type...
ISITWENTY (to reveal entire map)
ISILETSBAIL (to end the current level)
ISIWHEELS (gives you the INCREDIBLE custom configurable X-Car! Can you say Kick Butt?) (You must win the mission to get access to the X-Car.)
ISIFATPACKED (Gives all weapons, ammo, and powerups)
ISIQ (GOD MODE!)
ISISLEEP (Freezes enemy's dead in their tracks)