| Region | Title | System | Version | Edition | Languages | Serial | Status |
|---|
 | Obbligato (Taikenban CD-ROM)
オブリガート 体験版CD-ROM | PC | | Demo |  | |  |
 | Obsidian | PC | 1.0 | Demo |  | | |
| Oddworld: Abe's Oddysee | PSX | | Trade Demo | | | |
| Official Sega Dreamcast Magazine Vol. 11: February 2001 | DC | 0.500 | | | | |
| Official Sega Dreamcast Magazine Vol. 5: May 2000 | DC | 1.010 | | | | |
 | Olympic Games | 3DO | | Bundled with Magazine (Demo) | | | ![2 and more dumps from original media [!]](/images/status/green.png "2 and more dumps from original media [!]") |
 | Omgaan met Steriele Medische Hulpmiddelen | CDI | | Demo | | | |
| On the Rain-Slick Precipice of Darkness: Episode One | PC | | Demo | | | |
 | One Must Fall 2097 | PC | | Demo: JukeBox Collection | | | |
| One Must Fall 2097 | PC | 1.1 | Demo |  | | |
| Only You: Sekai no Namida to Shoujo no Hanashi: Prelude
Ｏｎｌｙ Ｙｏｕ －世界の涙と少女のハナシ－ Ｐｒｅｌｕｄｅ | PC | 1.00 | Trial Edition version:share II | | | |
 | Open Season
Boog & Elliot | PC | 1.0 | Demo |     | | |
| Operation Body Count: One Level Preview | PC | | Original | | | |
| Optimum Resource Sampler | PC | | Rerelease | | | |
| Optimum Resource Sampler | PC | | Original | | | |
| Orchid Technology Kelvin MPEG Software Catalog | PC | | | | | |
| Osananajimi wa Pet Yakuza!
幼なじみはペットヤクザ！体験版 | PC | | Taikenban | | | |
 | Osef Minei Mischakim
אוסף מיני משחקים | PC | | Original | | | |
| Otome Koigokoro Prister
乙女恋心プリスター体験版 | PC | | Taikenban | | | |
 | Over 1000 Games: The Complete Encyclopedia of Games: Volume II (Disc 1)
Over 1000 Games Volume 2 | PC | | Original | | | |
| Over 1000 Games: The Complete Encyclopedia of Games: Volume II (Disc 2)
Over 1000 Games Volume 2 | PC | | Original | | | |
| Over 200 Programs for Windows
STG Computers LTD Windows Extra CD-ROM | PC | | Original | | | |
| Oni / 4x4 Evo
Oni / 4x4 Evolution | PC | | Demo | | 12DC1-09GM03-11 | |
| Outlaws (Demonstration Program) | PC | Demo 1.0 CD Build 3 | Demo | | 644230 | |
| Official Sega Dreamcast Magazine Vol. 2: November 1999 | DC | 1.020 | | | IGN1 | |
| Official Sega Dreamcast Magazine Vol. 10: January 2001 | DC | 1.200 | | | IGN10 | |
| Official Sega Dreamcast Magazine Vol. 3: January 2000 | DC | 1.010 | | | IGN2 | |
| Official Sega Dreamcast Magazine Vol. 4: March 2000 | DC | 1.020 | | | IGN3 | |
| Official Sega Dreamcast Magazine Vol. 6: July 2000 | DC | 1.050 | | | IGN6 | |
| Official Sega Dreamcast Magazine Vol. 7: September 2000 | DC | 1.020 | | | IGN7 | |
| Official Sega Dreamcast Magazine Vol. 8: November 2000 | DC | 1.020 | | | IGN8 | |
| Official Sega Dreamcast Magazine Vol. 9: December 2000 | DC | 1.000 | | | IGN9 | |
 | The Official Xbox Magazine: Australia & New Zealand: Issue 101 | XBOX360 | | | | IM-2147 | |
| The Official Xbox Magazine: Australia & New Zealand: Issue 106 | XBOX360 | | | | IM-2152 | |
| The Official Xbox Magazine: Australia & New Zealand: Issue 108 | XBOX360 | | | | IM-2154 | |
| The Official Xbox Magazine: Australia & New Zealand: Issue 109 | XBOX360 | | | | IM-2155 | |
| OverBlood 2
オーバーブラッド２ | PSX | | Special Movie-ban | | PAPX 90046 … | |
| Omega Boost
オメガ・ブースト | PSX | | Taikenban | | PAPX 90080 | |
| Ore no Ryouri
俺の料理 | PSX | | Taikenban | | PAPX 90084 | |
| Ore no Ryouri
俺の料理 | PSX | | Taikenban | | PAPX 90089 | |
| Otostaz
オトスタツ | PS2 | 1.00 | Taikenban | | PAPX 90226 | |
| Otostaz
オトスタツ | PS2 | 1.00 | Taikenban | | PAPX 90228 | |
| Official Disc 2003 | PS2 | 1.01 | Taikenban | | PAPX 90507 | |
| Ore no Shikabane o Koete Yuke
俺の屍を越えてゆけ | PSX | | Tentou-you Movie Disc | | PCPX 96160 | |
| Operation Flashpoint: Cold War Crisis | PC | | Playable Demo | | POPFCDUS40 | |
| Oops! Prank Party | WII | | Demo |   | RVL-DPIE-USA-B0 | |
| OPSM Best Racing Game Ever | PSX | | | | SCED-02492 | |
| OPSM Best Ever Ever Games Demo | PSX | | Demo | | SCED-02851 | |
 | Official UK PlayStation Best Games Ever! | PSX | | | | SCED-03408 | |
| Official Demo Disc 1: Retail Edition November 01 | PS2 | 1.04 | Kiosk Demo | | SCED-50615 | |
| Official Demo Disc Retail Edition February 02
official demo disc retail edition february 02 | PS2 | 1.02 | |  | SCED-50732 | |
 | Official PlayStation 2 Magazine Demo 32
PlayStation 2 Revista Oficial: Portugal 9 | PS2 | 1.00 | | | SCED-51657 | |
| Otostaz
オトスタツ | PS2 | 1.00 | Taikenban | | SCPS 11020 | |
| OutRun 2 | XBOX | | Demo | | SE-057 | |
| Oddworld: Abe's Oddysee | PSX | | Demo | | SLED-00725 | |
| One | PSX | | Demo | | SLED-01170 | |
| O.D.T. | PSX | | Demo | | SLED-01574 | |
 | O.D.T. | PSX | | Demo | | SLED-01575 | |
| Oddworld: Abe's Exoddus + Duke Nukem: Time To Kill + B-Movie | PSX | | Demo | | SLED-01608 | |
| Oddworld: Abe's Exoddus + Duke Nukem: Time to Kill + Duke Nukem: 3D | PSX | | | | SLED-01655 | |
| Onimusha
鬼武者 | PS2 | 1.01 | Taikenban | | SLPM 61001 | |
| Ookami: Fude-hajime no Maki
大神 筆はじめノ巻 | PS2 | 1.01 | Taikenban | | SLPM 61124 | |
| Over Drivin' DX: Rally Edition
オーバードライビンＤＸ ラリーエディション | PSX | | Hibaihin | | SLPM 80032 | |
| Odo Odo Oddity
おどおど おっでぃ | PSX | | Hibaihin | | SLPM 80075 | |
| Ore! Tomba
オレっ！トンバ | PSX | | Taikenban | | SLPM 80165 | |
| Option: Tuning Car Battle
Ｏｐｔｉｏｎ チューニングカーバトル | PSX | | Highlight-ban | | SLPM 80203 | |
| Option: Tuning Car Battle
Ｏｐｔｉｏｎ チューニングカーバトル | PSX | | Taikenban | | SLPM 80206 | |
| Ojousama Express
お嬢様特急 | PSX | | Taikenban | | SLPM 80255 | |
| Over Drivin' III: Hot Pursuit
オーバードライビンⅢ | PSX | | Taikenban Disc | | SLPM 80298 | |
| Over Drivin' IV
オーバードライビンⅣ | PSX | | Taikenban Disc | | SLPM 80437 | |
| One Piece Mansion
ワンピースマンション | PSX | | Taikenban | | SLPM 80617 | |
| Odin Sphere | PS2 | 1.00 | Trade Demo | | SLUS-28065 | |
| Oddworld: Abe's Oddysee | PSX | | Demo | | SLUS-90004 | |
| O.D.T. | PSX | | Demo | | SLUS-90043 | |
