Region | Title | System | Version | Edition | Languages | Serial | Status |
| Ohio Distinctive Software Vol. I | PC | | | | | |
| Online Start-Up Disc 4.0: Broadband Only | PS2 | 1.02 | Bundled with PS2 | | PBPX 95248 … | |
| The Operative: No One Lives Forever (Disc 1) | PC | 1.004 | Game of the Year Edition | | | |
| 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 | |
| Overwatch | PC | | Game of the Year Edition, Legendary Edition | | 73052010US, S7302210 | |
| Operation | PC | | General Mills | | AM801R5 | |
| The Official Guide to Babylon 5 The Official Guide to J. Michael Straczynski's Babylon 5 | PC | | Original | | | |
| Oh Yes... More Worms! Volume 1 | ACD | | Original | | | |
| Oil Tycoon | PC | 1.01 | Original | | | |
| One Piece: Pirates Carnival ワンピース パイレーツカーニバル | GC | | Original | | DL-DOL-GIPJ-JPN | |
| Operation Flashpoint: Cold War Crisis | PC | 1.0 | Original | | MOPFCDUS00 | |
| Operation Flashpoint: Gold Upgrade | PC | 1.30 | Original | | MOFUCDUS00 | |
| Operation Flashpoint: Resistance | PC | 1.75 | Original | | MOFRCDUS00 | |
| Outpost 2: Divided Destiny | PC | 1.2.0.5 | Original | | | |
| Over 1000 Games: The Complete Encyclopedia of Games (Disc 1) | PC | | Original | | | |
| Over 1000 Games: The Complete Encyclopedia of Games (Disc 2) | PC | | Original | | | |
| Overlord II | XBOX360 | | Original | | CM-2057 | |
| Obsidian (Disc 1) | PC | | Original, Complimentary Copy | | 11008 | |
| Obsidian (Disc 2) | PC | | Original, Complimentary Copy | | 11008 | |
| Obsidian (Disc 3) | PC | | Original, Complimentary Copy | | 11008 | |
| Obsidian (Disc 4) | PC | | Original, Complimentary Copy | | 11008 | |
| Obsidian (Disc 5) | PC | | Original, Complimentary Copy | | 11008 | |
| Oregon Trail II: 25th Anniversary Limited Edition | PC | 1.3 | Original, SoftKey | | #OTR744AE-CD | |
| Overwatch | PC | | Origins Edition | | | |
| The Oregon Trail 4th Edition (Disc 1) | PC | 1.1 | Rerelease | | OTF744BE-CD1 | |
| The Oregon Trail 4th Edition (Disc 2) | PC | 1.1 | Rerelease | | OTF744BE-CD2 | |
| The Oregon Trail 4th Edition (Disc 3) | PC | 1.1 | Rerelease | | OTF744BE-CD3 | |
| Outpost | PC | 1.5 | Rerelease, Sierra Originals | | | |