| .RMO | Iron Crown Enterprises | Pelitiedostot | Rolemaster Character Data | Rolemaster | Iron Crown Enterprises |
| .ROD | RIB Software | Pelitiedostot | RIB Office Database File | RIB office | RIB Software |
| .ROS | Jon Taylor | Pelitiedostot | BattleScribe Roster Editor File | BattleScribe | Jon Taylor |
| .ROT | Sierra Entertainment | Pelitiedostot | Homeworld 2 Graphics File | Homeworld 2 | Sierra Entertainment |
| .RP2 | Cloanto Corporation | Pelitiedostot | RetroPlatform Player Program Archive | Amiga Forever | Cloanto Corporation |
| .RPF | Rockstar Games | Pelitiedostot | Grand Theft Auto Data File | Grand Theft Auto IV | Rockstar Games |
| .RPL | Nabi Studios | Pelitiedostot | Toribash Replay File | Toribash | Nabi Studios |
| .RPX | Cemu | Pelitiedostot | Wii U Game | Cemu | Cemu |
| .RPY | Team Shanghai Alice | Pelitiedostot | Touhou Project Replay File | Touhou Project | Team Shanghai Alice |
| .RPYC | Tom "PyTom" Rothamel | Pelitiedostot | Ren'Py Compiled Script | Ren'Py | Tom "PyTom" Rothamel |
| .RRS | Electronic Arts | Pelitiedostot | Road Rash Saved Game Position | Road Rash | Electronic Arts |
| .RSD | Rosetta Stone | Pelitiedostot | Rosetta Stone Data File | Rosetta Stone Language Learning | Rosetta Stone |
| .RSG | Surreal Software | Pelitiedostot | Drakan: Order Of The Flame File | Drakan: Order Of The Flame | Surreal Software |
| .RSH | Relic Entertainment | Pelitiedostot | Warhammer 40,000 Texture | Warhammer 40K Dawn of War | Relic Entertainment |
| .RUN | Open Source | Pelitiedostot | Linux Executable File | Linux | Open Source |
| .RVI | Eidos Interactive | Pelitiedostot | Revenant Game Archive | Revenant | Cinematix Studios, Inc. |
| .RVM | Eidos Interactive | Pelitiedostot | Revenant Game Archive | Revenant | Cinematix Studios, Inc. |
| .RVN | Cyan | Pelitiedostot | Riven Saved Game | Riven | Cyan |
| .RVS | Eidos Interactive | Pelitiedostot | Revenant Game Archive | Revenant | Cinematix Studios, Inc. |
| .RW | Open Source | Pelitiedostot | BVE Trainsim Railway Definition File | CyberLink PowerDVD | CyberLink |
| .RWD | NRG Systems | Pelitiedostot | NRG Raw Wind Data File | Symphonie Data Retriever | NRG Systems |
| .RWS | Ludeon Studios | Pelitiedostot | RimWorld Game Save File | Ludeon Studios RimWorld | Ludeon Studios |
| .RX3 | EA Maxis | Pelitiedostot | FIFA Texture File | FIFA 14 | EA Sports |
| .RXDATA | Kadokawa Corporation | Pelitiedostot | RMXP Data File | Enterbrain RPG Maker XP (RMXP) | Kadokawa Corporation |
| .S11 | Interplay Entertainment | Pelitiedostot | Descent 2 Game Data | Interplay Descent 2 | Interplay Entertainment |
| .S16 | Sports Interactive | Pelitiedostot | Football Manager Game Data | Football Manager 2016 | Sports Interactive |
| .S2 | Motorola | Pelitiedostot | Motorola S-record Format | Unknown Software | Unknown Developer |
| .S2R | Unknown Developer | Pelitiedostot | RegMagik File | RegMagik | Unknown Developer |
| .S3R | 49Games | Pelitiedostot | RTL Ski Jumping Replay File | RTL Ski Jumping | 49Games |
| .S4M | Irrational Games | Pelitiedostot | SWAT 4 Map File | SWAT 4 | Irrational Games |
| .SA1 | VBA Team | Pelitiedostot | Game Boy Emulator Save File | VisualBoyAdvance | VBA Team |
| .SABS | Activision | Pelitiedostot | Call Of Duty: Black Ops Sound Archive | Call of Duty: Black Ops | Activision |
| .SACRED2SAVE | Ascaron Entertainment | Pelitiedostot | Sacred 2 Saved Game | Sacred 2: Fallen Angel | Ascaron Entertainment |
| .SAD | LucasArts Entertainment Company, LLC | Pelitiedostot | Lucas Arts Sound Data | Dragon UnPACKer | Open Source |
| .SAK | Running With Scissors | Pelitiedostot | Postal Game Archive | Postal | Running With Scissors |
| .SAN | LucasArts Entertainment Company, LLC | Pelitiedostot | Smush Animation File | Star Wars: Rebel Assault | LucasArts Entertainment Company, LLC |
| .SAV | Nintendo | Pelitiedostot | Saved Game File | No Cash GBA (No$GBA) | Martin Korth |
| .SAZ | Microsoft Corporation | Pelitiedostot | Fiddler Session Archive ZIP Data | Fiddler | Microsoft Corporation |
| .SBF | Google | Pelitiedostot | Android System File | Google Android | Google |
| .SBM | Keen Software House | Pelitiedostot | Space Engineers Mod File | Space Engineers | Keen Software House |
| .SC2 | EA Maxis | Pelitiedostot | SimCity 2000 City File | Maxis SimCity 2000 | EA Maxis |
| .SC3 | EA Maxis | Pelitiedostot | SimCity 3000 City File | Maxis SimCity 3000 | EA Maxis |
| .SC4 | Chris Sawyer | Pelitiedostot | RollerCoaster Tycoon Scenario File | RollerCoaster Tycoon 3 | Frontier Developments plc |
| .SC4DESC | Electronic Arts | Pelitiedostot | SimCity 4 Description File | Electronic Arts SimCity 4 | Electronic Arts |
| .SC4LOT | Electronic Arts | Pelitiedostot | SimCity 4 Lot File | Electronic Arts SimCity 4 | Electronic Arts |
| .SC6 | Chris Sawyer | Pelitiedostot | RollerCoaster Tycoon 2 Scenario File | RollerCoaster Tycoon 2: Triple Thrill Pack | Chris Sawyer |
| .SCENE | Fandom | Pelitiedostot | Antibody Level File | Hidden Temple Studios Antibody | Fandom |
| .SCF | Microsoft Corporation | Pelitiedostot | Windows Explorer Command | Microsoft Windows | Microsoft Corporation |
| .SCM | Gimpel Software | Pelitiedostot | GIMP Script-Fu Script | GIMP | The GIMP Development Team |
| .SCN | Microsoft Corporation | Pelitiedostot | Age Of Mythology Scenario File | Microsoft Age of Empires | Ensemble Studios |
| .SCO | MR Software | Pelitiedostot | OMSI Scenery Object Configuration File | OMSI | MR Software |
| .SCS | Electronic Arts | Pelitiedostot | SimCity Societies Saved Game File | SimCity Societies | Tilted Mill Entertainment |
| .SCX | RIX SoftWorks, Inc. | Pelitiedostot | ColoRIX Bitmap Graphic File | XnView MP | XnSoft |
| .SCZ | OpenLimit SignCubes AG | Pelitiedostot | OpenLimit SignCubes Zip Container File | OpenLimit CC Sign | OpenLimit SignCubes AG |
| .SD7 | Unknown Developer | Pelitiedostot | Spring RTS Engine Data File | Spring | Open Source |
| .SDF | Microsoft Corporation | Pelitiedostot | SQL Server Compact Database File | Microsoft Visual Studio | Microsoft Corporation |
| .SDP | Oracle Corporation | Pelitiedostot | StarOffice Presentation File | Apache OpenOffice | Apache Software Foundation |
| .SDT | Intuit, Inc. | Pelitiedostot | QuickBooks Data File | Intuit QuickBooks Pro | Intuit, Inc. |
| .SEP | PictView software | Pelitiedostot | Separated Image File | PictView | PictView software |
| .SFB | Sony | Pelitiedostot | PlayStation 3 Disc Data File | Microsoft Notepad | Microsoft Corporation |
| .SFC | Unknown Developer | Pelitiedostot | Super Nintendo ROM | Snes9x | Snes9x Team |
| .SFF | Elecbyte | Pelitiedostot | M.U.G.E.N. Sprite File | Elecbyte M.U.G.E.N | Elecbyte |
| .SFL | Magix Software GmbH | Pelitiedostot | Sound Forge Pro Sound Data File | MAGIX Vegas | Magix Software GmbH |
| .SFO | Interscape | Pelitiedostot | PSP Game Parameters File | PBP Unpacker | Unknown Developer |
| .SFS | Open Source | Pelitiedostot | Squashfs File Archive | 7-Zip | Igor Pavlov |
| .SG | Unknown Developer | Pelitiedostot | SG-1000 Game ROM File | Kega Fusion | Steve Snake |
| .SGA | Relic Entertainment | Pelitiedostot | Relic Entertainment Game Archive | Relic Entertainment Dawn of War | Relic Entertainment |
| .SGB | Relic Entertainment | Pelitiedostot | Dawn Of War Map File | Relic Entertainment Dawn of War | Relic Entertainment |
| .SGI | Silicon Graphics, Inc. | Pelitiedostot | Silicon Graphics Image File | Canvas X | ACD Systems |
| .SGM | VBA Team | Pelitiedostot | VisualBoyAdvance Saved Game | VisualBoyAdvance | VBA Team |
| .SGR | Electronic Arts | Pelitiedostot | SimCity 4 Graphics Rules File | Electronic Arts SimCity 4 | Electronic Arts |
| .SHADER | id Software | Pelitiedostot | Quake 3 Arena Id Tech 3 Game Engine Shader File | Quake 3 Arena | id Software |
| .SID | Valve | Pelitiedostot | Steam Game Data Backup File | Steam | Valve |
| .SII | SCS Software | Pelitiedostot | 18 Wheels Of Steel: Haulin' Truck Definition File | SCS 18 Wheels of Steel: Haulin' | SCS Software |
| .SIMS2PACK | Electronic Arts | Pelitiedostot | Downloaded Sims 2 Package File | Electronic Arts The Sims 2 | Electronic Arts |
| .SIN | Big Huge Games | Pelitiedostot | Rise Of Nations Campaign Media File | Rise Of Nations | Big Huge Games |
| .SKD | Rockstar Games | Pelitiedostot | Max Payne Skin Data File | chUmbaLum sOft MilkShape 3D | chUmbaLum sOft |
| .SKN | Avant Force | Pelitiedostot | Avant Browser Skin File | Avant Browser | Avant Force |
| .SLF | Symantec Corporation | Pelitiedostot | Symantec License File | Symantec Ghost Solution Suite | Symantec Corporation |
| .SLH | BioWare | Pelitiedostot | Baldur's Gate II Game Data | Baldur's Gate | BioWare |
| .SLI | MR Software | Pelitiedostot | OMSI Spline Configuration File | OMSI 2 | MR Software |
| .SLM | Morrison Software | Pelitiedostot | Gallery Lock Hidden Media | Gallery Lock Pro | Morrison Software |
| .SLP | Magix Software GmbH | Pelitiedostot | SpectraLayers Pro Project | SpectraLayers Pro | Magix Software GmbH |
| .SM | Open Source | Pelitiedostot | StepMania Song File | StepMania | Open Source |
| .SMC | Snes9x Team | Pelitiedostot | Super Nintendo Game ROM | Snes9x | Snes9x Team |
| .SMD | Valve | Pelitiedostot | Valve Studiomdl Data File | Microsoft Notepad | Microsoft Corporation |
| .SMK | RAD Game Tools | Pelitiedostot | Smacker Compressed Movie File | RAD Video Tools | RAD Game Tools |
| .SMO | Gravitysensation.com | Pelitiedostot | Sumotori Dreams Arena File | Sumotori Dreams | Gravitysensation.com |
| .SMS | Sega | Pelitiedostot | Sega Master System ROM | Kega Fusion | Steve Snake |
| .SMV | Smith Micro Software | Pelitiedostot | VideoLink Mail Video File | Smith Micro Videolink Pro | Smith Micro Software |
| .SMZIP | Open Source | Pelitiedostot | StepMania Package | StepMania | Open Source |
| .SNA | Tom Ehlert Software | Pelitiedostot | Drive Snapshot Primary Backup File | Tom Ehlert Drive Snapshot | Tom Ehlert Software |
| .SND | Open Source | Pelitiedostot | Sound File | Microsoft Windows Media Player | Microsoft Corporation |
| .SNI | Interplay Entertainment | Pelitiedostot | MDK Game Archive | MDK | Interplay Entertainment |
| .SNT | Microsoft Corporation | Pelitiedostot | Microsoft Windows Sticky Notes File | Sticky Notes | Microsoft Corporation |
| .SOD | id Software | Pelitiedostot | Spear Of Destiny Data File | Spear of Destiny | id Software |
| .SOK | Open Source | Pelitiedostot | Sokoban++ Level File | Sokoban | Open Source |
| .SOT | Human Entertainment | Pelitiedostot | Adventure SOS Adventure Game Walkthrough Source File | SOS (1993 video game) | Human Entertainment |
| .SOU | LucasArts Entertainment Company, LLC | Pelitiedostot | Lucas Arts Sound Data | Dragon UnPACKer | Open Source |
| .SOUNDS | id Software | Pelitiedostot | Quake 3 Engine Sound Definition File | Microsoft Notepad | Microsoft Corporation |
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