| .G3X | Knife Edge Software | File di giochi | RealFlight Content File | RealFlight | Knife Edge Software |
| .G4B | Open Source | File di giochi | Sokoban++ Level File | Sokoban | Open Source |
| .GAM | Nintendo | File di giochi | Saved Game File | No Cash GBA (No$GBA) | Martin Korth |
| .GAME | Apple | File di giochi | Apple Chess Saved Game | Apple Chess | Apple |
| .GAR | GIANTS Software | File di giochi | Farming Simulator Game Archive File | Farming Simulator | GIANTS Software |
| .GAX | Microsoft Corporation | File di giochi | Age Of Empires II Saved Game | Microsoft Age of Empires | Ensemble Studios |
| .GBA | Unknown Developer | File di giochi | Game Boy Advance ROM | No Cash GBA (No$GBA) | Martin Korth |
| .GBC | VBA Team | File di giochi | Game Boy Color ROM | VisualBoyAdvance | VBA Team |
| .GBX | Nadeo | File di giochi | Nadeo Game File | TrackMania | Nadeo |
| .GC | Arizona | File di giochi | GraphClick File | GraphClick | Arizona |
| .GCD | General CADD Products | File di giochi | Generic CADD Drawing File | General CADD Pro | General CADD Products |
| .GCF | Valve | File di giochi | Game Cache File | Steam | Valve |
| .GCI | Nintendo | File di giochi | GameCube Save File | Dolphin (emulator) | Dolphin Emulator Project |
| .GCM | Nintendo | File di giochi | GameCube ROM | Dolphin (emulator) | Dolphin Emulator Project |
| .GCS | Dolphin Emulator Project | File di giochi | GameCube SharkSave File | Dolphin (emulator) | Dolphin Emulator Project |
| .GCT | Interscape | File di giochi | Ocarina Cheat Code Manager Exported Cheat | Ocarina Cheat Code Manager | Interscape |
| .GCV | thriXXX | File di giochi | SexVilla Game Movie | SexVilla | thriXXX |
| .GDB | Garmin | File di giochi | GPS Database File | Garmin BaseCamp | Garmin |
| .GDF | Eytan Adar | File di giochi | GUESS Graph Data Format File | GUESS | Eytan Adar |
| .GDG | Interscape | File di giochi | GDevelop Project File | GDevelop | Interscape |
| .GDI | Open Source | File di giochi | Dreamcast Gigabyte Disc Image | nullDC | Open Source |
| .GDW | Appaloosa Interactive | File di giochi | Jaws Unleashed Data File | Jaws Unleashed | Appaloosa Interactive |
| .GEN | Sega | File di giochi | Sega Genesis ROM | Kega Fusion | Steve Snake |
| .GFX | Autodesk, Inc. | File di giochi | GFx Scaleform File | Scaleform GFx | Autodesk, Inc. |
| .GG | Google | File di giochi | Google Desktop Gadget File | Google Desktop | Google |
| .GGS | Nintendo | File di giochi | Gameboy Emulator File | No Cash GBA (No$GBA) | Martin Korth |
| .GHB | High Voltage Software | File di giochi | Lego Ghost Path File | High Voltage Software LEGO Racers | High Voltage Software |
| .GHS | Symantec Corporation | File di giochi | Norton Ghost Image Segment Backup File | Symantec Ghost Solution Suite | Symantec Corporation |
| .GIC | BioWare | File di giochi | BioWare Aurora Engine Area Data | BioWare Neverwinter Nights | BioWare |
| .GJD | Trilobyte | File di giochi | The 7th Guest Media File | The 7th Guest | Trilobyte |
| .GL | John Bridges | File di giochi | GRASP Animation | Dassault Systemes CATIA | Dassault Systèmes |
| .GLB | Analytical Graphics | File di giochi | STK Globe File | Systems Tool Kit (STK) | Analytical Graphics |
| .GM1 | New World Computing | File di giochi | Heroes Of Might & Magic III Saved Game | Heroes of Might & Magic III | Ubisoft |
| .GM2 | New World Computing | File di giochi | Heroes Of Might & Magic III Saved Game | Heroes of Might & Magic III | Ubisoft |
| .GM3 | New World Computing | File di giochi | Heroes Of Might & Magic III Saved Game | Heroes of Might & Magic III | Ubisoft |
| .GM4 | New World Computing | File di giochi | Heroes Of Might & Magic III Saved Game | Heroes of Might & Magic III | Ubisoft |
| .GM7 | New World Computing | File di giochi | Heroes Of Might & Magic III Saved Game | Heroes of Might & Magic III | Ubisoft |
| .GM8 | New World Computing | File di giochi | Heroes Of Might & Magic III Saved Game | Heroes of Might & Magic III | Ubisoft |
| .GMA | Garry Newman | File di giochi | Garry's Mod Addon File | Facepunch Studios Garry's Mod | Garry Newman |
| .GME | InterAct | File di giochi | DexDrive Game Card File | InterAct DexDrive | InterAct |
| .GMP | Blue Marble Geographics | File di giochi | Global Mapper Package File | Global Mapper | Blue Marble Geographics |
| .GMV | GenSoft | File di giochi | Gens Game Recording | Gens | Open Source |
| .GOD | 4D, Inc | File di giochi | Gore Game Data File | Gore: Ultimate Soldier | 4D, Inc |
| .GODD | Games On Demand Pty. Ltd. | File di giochi | Partial Downloaded Game File | G.O.D Arena | Games On Demand Pty. Ltd. |
| .GOO | LucasArts Entertainment Company, LLC | File di giochi | Jedi Knight: Mysteries Of The Sith Game Data | Jedi Knight: Mysteries of The Sith | Valve |
| .GPD | Microsoft Corporation | File di giochi | Generic Printer Description File | Microsoft Windows | Microsoft Corporation |
| .GPF | Open Source | File di giochi | Gecko Patch File | Nintendulator | Open Source |
| .GPM | GRAVITY | File di giochi | Ragnarok Online Update File | Ragnarok Online | GRAVITY |
| .GR2 | Larian Studios | File di giochi | Divinity: Original Sin Game Data | Divinity: Original Sin | Larian Studios |
| .GRA | Microsoft Corporation | File di giochi | Microsoft Graph File | Microsoft Excel | Microsoft Corporation |
| .GRF | GRAVITY | File di giochi | Ragnarok Client Archive | Ragnarok Online | GRAVITY |
| .GRN | RAD Game Tools | File di giochi | Granny 3D File | Granny 3D | RAD Game Tools |
| .GRO | Open Source | File di giochi | Allegro MIDI File | Audacity | Open Source |
| .GRP | Blizzard Entertainment Inc. | File di giochi | StarCraft Graphics Group File | StarCraft | Blizzard Entertainment Inc. |
| .GRS | Headlight Software | File di giochi | GetRight Skin | GetRight | Headlight Software |
| .GRV | Microsoft Corporation | File di giochi | Office Groove File | Microsoft Office Groove | Microsoft Corporation |
| .GS0 | Sega | File di giochi | Sega Genesis Emulator Quick Slot 0 Save File | Kega Fusion | Steve Snake |
| .GSC | Activision | File di giochi | Call Of Duty Game Script | Notepad++ | Don Ho |
| .GST | MapInfo Corporation | File di giochi | MapInfo Geoset File | MapInfo Professional | Pitney Bowes |
| .GSV | Mad Catz | File di giochi | GameShark Saved Game | Unknown Software | Unknown Developer |
| .GSX | Sega | File di giochi | Sega Genesis Emulator Saved State File | Kega Fusion | Steve Snake |
| .GUT | GUT GmbH | File di giochi | ASSISTANT Data File | ASSISTANT | GUT GmbH |
| .GVR | GeoVisu Development Team | File di giochi | GeoVisu Routes File | GeoVisu | GeoVisu Development Team |
| .GZP | Interplay Entertainment | File di giochi | Giants Citizen Kabuto Game File | Giants: Citizen Kabuto | Interplay Entertainment |
| .GZR | MAIET Entertainment | File di giochi | GunZ File | MAIET Entertainment GunZ | MAIET Entertainment |
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