While on an away mission (other then the beginning rescue mission) type: ` (the key next to 1)

*to bring up the display and then
type: god
*for god mode or
type: give all
*for all ammo and weapons
DISABLE CHEATS- sv_cheats 0
FLY AROUND AND WALK THROUGH WALLS- noclip
999 AMOUR AND 999 HEALTH- undying
THE ENEMIES CAN'T SEE YOU- notarget
GET THE CURRENT GRAVITY LEVELS- g_gravity
CHANGE THE GRAVITY LEVELS- g_gravity #
KILL YOURSELF- kill