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.
Here are the 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

G-Police:
*Enter codes at the main menu:
BENIHILL: toggles Benny Hill cars.
DOOBIES: toggles infinite shields (disables mission progression).
MRTICKY: toggles infinite weapons (disables mission progression).
PANTALON: grants access to all secret missions via the training menu.
STATTOE: provides in game stats.
SUPACAM: toggles enemy fall cam.
WOOWOO: toggles havoc sirens.
*Level codes:
MADGAV: level 1.
DOLMAN: level 2.
SONAGAV: level 3.
ACEDUF: level 4.
JOJOGUN: level 5.
WENSKI: level 6.
SAEGGY: level 7.
MAZMAN: level 8.
DAZMAN: level 9.
DELUCS: level 10.
ANDOOOO: level 11.
KIMBCHS: level 12.
ANDYMAC: level 13.
YERMAN: level 14.
OLLIEB: level 15.
THEYOLK: level 16.
TONYMASH: level 17.
ANDYCROW: level 18.
BIONIC: level 19.
TSLATER: level 20.
IAINTHOD: level 21.
JONRITZ: level 22.
CLAIREC: level 23.
STEVEBOT: level 24.
ANGUSF: level 25.
EUANLEC: level 26.
EDFIRE: level 27.
STUBOMB: level 28.
THONBOY: level 29.
JIMMAC: level 30.
PUGGER: level 31.
ROSSCO: level 32.
CAKEBOY: level 33.
NIKNAK: level 34.
SAGLORD: level 35.

Gender Wars:
*At the options screen, select save game and enter the following codes as saves to activate cheats:
BUY A PLAYSTATION: invulnerability, infinite energy and all weapons.
WORLD OF FISH: level warp. After you've entered the codes, quit to title and start a new game. The cheats will still be enabled.

Gene Wars:
*Type SALMONAXE during gameplay to activate cheatmode. Tap the keys listed below to activate the cheats.
C: gives access to all hybrids and purebreds.
D: gives memory statistics.
L: summons more monoliths.
T: makes structures translucent.
W: win. successfully completes the current mission.

Get Medieval:
* Type these codes:
mpkfa - God Mode
mppos - Global position
mpfps - Frames per second

Gex:
* The following are level codes.
SVZFKHGP: cemetery 1.
BXRFYHGP: cemetery 2.
KXVKRHKP: jungle isle 1.
SVKLPHKP: jungle isle 2.
CVBLPHKP: jungle isle 3.
ZVTCYHGP: new toonland 1.
CVHCSHKP: new toonland 2.
RVTCSHGP: new toonland 3.
CVBLPHKP: new toonland 4.
YTCHPHKP: kung fuville 1.
ZTDHPHKP: kung fuville 2.
DXVGRHKP: kung fuville 3.
GYVYRHKP: rezopolis 1.

Gobliiins:
VQVQFDE: level 2.
ICIGCAA: level 3.
ECPQPCC: level 4.
FTWKFEN: level 5.
HQWFTFW: level 6.
DWNDGBW: level 7.
JCJCJHM: level 8.
ICVGCGT: level 9.
LQPCUJV: level 10.
HNWVGKB: level 11.
FTQKVLE: level 12.
DCPLQMH: level 13.
EWDGPNL: level 14.
TCNGTOV: level 15.
TCVQRPM: level 16.
IQDNKQO: level 17.
KKKPURE: level 18.
NGOGKSP: level 19.
NNGWTTO: level 20.
LGWFGUS: level 21.
TQNGFVC: level 22.

Grand Theft Auto:
*Enter the following codes at the character select screen, press [DEL] and enter the name.
6031769: grants unlimited lives.
BUCKFAST: * on the keypad grants all weapons.
CALLMENIGEL: ???
HATE MACHINE: raises all point values.
IAMGARYPENN: ???
IAMNOTGARYPENN: ???
IAMTHELAW: eliminates police.
ITCOULDBEYOU: grants 999999999 points.
ITSGALLUS: grants access to all levels and cities.
ITSTANTRUM: grants unlimited lives.
NINEINAROW: grants access to all levels and cities.
PORKCHARSUI: toggles diagnostic mode.
STEVESMATES: eliminates police.
SUCKMYROCKET: grants all weapons, full armor and a get out of jail free card
SUPER WELL: grants access to all levels and cities.

Greed:
ALLAHMODE: toggles god mode.
BEAVIS: skips ahead to one hundred points away from level finish.
BELFAST: kills all enemies.
GULLIVER: toggles midget mode.
KMFDM: grants full ammo.
RAVEN: grants full health.
OMNI: reveals entire map.

Grid Runner:
Level Codes:
10╨ 1881399214: forge
11╨ 3873611174: trepidaria
12╨ 2447659415: iris

Gubble:
*Type GUBBLEDCHEAT at the title screen to enable cheat mode.
*Enter the following codes from anywhere on a map.
F3: removes all blocks from map.
F9: warps you to the next city map.
*Enter the following codes from any launch pad.
END: takes you back ten levels.
HOME: advances you ten levels.
PAGE DOWN: warps to previous level.
PAGE UP: warps to next level.
*Enter the following codes during gameplay.
F8: toggles invincibility.
F9: completes the level.
+: speeds you up.
-: slows you down.

Guts N Garters:
*It must be all CAPITAL letters
type GUTS \DAVESCHEAT - all Weapons