Region | Title | System | Version | Edition | Languages | Serial | Status |
| O.D.T. | PC | | Original | | | |
| ObsCure | PC | 1.0 | Original | | 719 02 102 | |
| Oddworld: Abe's Exoddus (Play Disc) | PC | 2.0 | Original | | | |
| Oddworld: Abe's Exoddus (Play Disc) | PC | 2.0 | Budget, Covermount | | MMICDR 5280 | |
| Oddworld: Abe's Exoddus (Install Disc) | PC | 2.0 | Original | | | |
| Oddworld: Abe's Exoddus (Disc 1) | PSX | | Original, Platinum | | SLES-01480 … | |
| Oddworld: Abe's Exoddus (Disc 2) | PSX | | Original, Platinum | | SLES-11480 … | |
| Oddworld: Abe's Exoddus + Duke Nukem: Time To Kill + B-Movie | PSX | | Demo | | SLED-01608 | |
| Oddworld: Abe's Oddysee | PSX | | Demo | | SLED-00725 | |
| Oddworld: Abe's Oddysee | PC | 2.0 | Original | | IB2G-ODD5 | |
| Official PlayStation 2 Magazine Demo 56 ops2m demo 56 | PS2 | 1.01 | | | SCED-53132 | |
| Official PlayStation 2 Magazine Demo 95 ops2m demo 95 eur | PS2 | 1.00 | | | SCED-55114 | |
| One Must Fall 2097 One Must Fall 2097 CD-ROM | PC | 1.1 | ROMWARE | | ROM 10017 | |
| One Must Fall 2097 | PC | 2.1 | The Smile Edition | | CDR3016 | |
| Oni | PC | 1.0 | Original | | | |
| Onside Complete Soccer | PSX | | Original | | SLES-00079 | |
| Operation Flashpoint: Cold War Crisis | PC | 1.0 | Original, Gold Edition | | MOPFCDEU00 | |
| Operation Flashpoint: Dragon Rising | PC | 1.0 | Original | | MOFP2CDEU00 | |
| The Operative: No One Lives Forever (Disc 1) | PC | 1.0 | Original | | FXX08903223D1 | |
| The Operative: No One Lives Forever (Disc 1) | PC | 1.004 | Game of the Year Edition (BestSeller Series) | | S0026178 | |
| The Operative: No One Lives Forever (Disc 2) | PC | 1.0 | Original | | FXX08903223D2 | |
| Oscar | PC | | Original | | | |
| Outcast (Disc 1) | PC | | Original | | OUTCAPC52G/A1 | |
| Outcast (Disc 2) | PC | | Original | | OUTCAPC52G/A2 | |
| Outlaws (Disc 1) | PC | 1.0 | Original | | 9511830 | |
| Outlaws (Disc 1) | PC | 2.0 | LucasArts Classics | | 3000009.101.UK | |
| Outlaws (Disc 2) | PC | 1.0 | Original | | 9511831 | |
| Outlaws (Disc 2) | PC | 2.0 | LucasArts Classics | | 3000009.102.UK | |
| Outlive | PC | 1.01 | Original | | | |
| Overboard! | PC | | Dice | | DCG 005752, DMM 005776 | |
| Official PlayStation 2 Magazine Demo 16 | PS2 | 1.00 | | | SCED-50151 | |
| Official PlayStation 2 Magazine Demo 22 | PS2 | 1.00 | | | SCED-50744 … | |
| Official PlayStation 2 Magazine Demo 23 | PS2 | 1.00 | | | SCED-50745 | |
| Official PlayStation 2 Magazine Demo 31 | PS2 | 1.02 | | | SCED-51529 | |
| Official PlayStation 2 Magazine Demo 32 | PS2 | 1.00 | | | SCED-51530 | |
| Official PlayStation 2 Magazine Demo 44 | PS2 | 1.01 | | | SCED-52052 … | |
| Official PlayStation 2 Magazine Demo 45 | PS2 | 1.02 | | | SCED-52160 | |
| Official PlayStation 2 Magazine Demo 46 | PS2 | 1.01 | | | SCED-52161 … | |
| Official PlayStation 2 Magazine Demo 57 ops2m demo 57 | PS2 | 1.00 | | | SCED-53228 … | |
| Official PlayStation 2 Magazine Demo 58 | PS2 | 1.00 | | | SCED-53288 | |
| Off Limits: Mizar | PC | | ROMWARE | | ROM 10120 | |
| Olympic Soccer | PC | | Kixx | | | |
| Outcast (Disc 1) | PC | | Limitierte Sonderausgabe | | OUTCAPC520/A1 | |
| Outcast (Disc 2) | PC | | Limitierte Sonderausgabe | | OUTCAPC520/A2 | |
| Outcast (Disc 3) | PC | | Limitierte Sonderausgabe | | OUTCAPC520/A3 | |
| Outlaws (Disc 1) | PC | 1.0 | Original | | | |
| Outlaws (Disc 1) | PC | 1.1 | Rerelease | | | |
| Outlaws (Disc 2) | PC | 1.0 | Original | | | |
| Outlaws (Disc 2) | PC | 1.1 | Rerelease | | | |
| Oddworld: Abe's Exoddus (Installatie Disk) | PC | 2.0 | Budget | | MMICDR 5280 | |
| Official PlayStation 2 Magazine Demo 101 ops2m demo 101 eur | PS2 | 1.00 | | | SCED-55120 | |
| Official PlayStation 2 Magazine Demo 73 ops2m demo 73/benelux | PS2 | 1.00 | | | SCED-54176 | |
| Operation Flashpoint: Cold War Crisis | PC | | The Games Collection | | | |
| Oxide Oxyde | PC | | Dynamite | | DE-006 | |
| Oddworld: Abe's Oddysee | PC | 2.0 | Original | | 04-12608CD | |
| One Must Fall 2097 | PC | | Original | | EPOMF01 | |
| One Unit Whole Blood | PC | 1.21 | Original | | 04-16459CD1 | |
| Operation Flashpoint: Gold Upgrade | PC | 1.30 | Original | | MOFUCDUS00 | |
| Outcast (Disc 1) | PC | | Original | | 42831-9110TC | |
| Outcast (Disc 2) | PC | | Original | | 42831-9110TC | |
| Operation Flashpoint: Gold Upgrade | PC | 1.30 | Original, Gold Edition | | MOFUCDEU00, MOFUCDUS00 | |
| The Operative: No One Lives Forever (Disc 2) | PC | 1.004 | Game of the Year Edition, Game of the Year Edition (BestSeller Series), Game of the Year Edition (Covermount) | | JCPL11, S0026179, S0026696 | |
| The Orange Box (Disc 1) | PC | | Original, EA Classics | | 985207, VAE07705811D, VAE07705811D/ENG, VAE07707118D/ENG, VAX07705811D/AUS | |
| Official PlayStation 2 Magazine Demo 62 | PS2 | 1.00 | | | SCED-53165 | |
| Official UK PlayStation Best Games Ever! | PSX | | | | SCED-03408 | |
| The Orange Box (Disc 2) | PC | | Original, EA Classics | | VAE07705811D2/ENG, VAE07707118D2/ENG, VAX07705811D2, VAX07705811D2/AUS | |