G-Nome

At the Mission computer press [Ctrl]+[F1].

Then You can enter one or more of the following codes.
All the codes are case sensitive!
Correct codes will be confirmed by a beep.

Codes:
Redtop Trod - Select all single player missions from the mission menu.
Half Libel - Activates Teleport key.
Had A Nude On - Activates Invincibility key.
Brass Clue - Activates Amunition Key.
Mother Mourn Us - Changes mountain on mission 1-5 to Mt. Rushmore with programers faces.
Chaste Coed - View the end video sequences.
Rotted Drop - Activates Destroy Target.
Horny Elk Leer - Activates all targets on radar key.
O'Sarge - Gives Seargeant in training missions an Irish accent.
Swiss Throat - Changes Citadel building into 7th level headquarters.
A Mere Fart - ???
A Scramble On - Let's you take screen shots by pressing SHIFT-CTRL-RIGHT CLICK.

In-Game-Keys :
[Ctrl]+[I] - Activates Invinciblity
[Ctrl]+[Z] - Refills ammo
[Ctrl]+[F] - Destroy current target
[Ctrl]+[B] - Teleport Behind Target
[Ctrl]+[P] - All targets on radar
(Information from Cheat Machine)