| Region | Title | System | Version | Edition | Languages | Serial | Status |
|---|
 | Obsidian (Disc 1) | PC | | Original, Complimentary Copy |  | 11008 | ![2 and more dumps from original media [!]](/images/status/green.png "2 and more dumps from original media [!]") |
| 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 | |
 | ODN Palm Power Pack | PALM | | Original | | |  |
| 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 | | | |
| Oh!X 1998 Spring Special CD-ROM (Part 2) (Sampler Disc) | X68K | | | | | |
| Oh!X 1998 Spring Special CD-ROM (Part 1) | X68K | | | | | |
| Oh!X 1999 Spring Special CD-ROM (Part 2) (Sampler Disc) | X68K | | | | | |
| Oh!X 1999 Spring Special CD-ROM (Part 1) | X68K | | | | | |
| Oh!X 1999 Summer Special CD-ROM | X68K | | | | | |
| Oh!X 2000 Spring Special CD-ROM (Part 2) | X68K | | | | | |
| Oh!X 2000 Spring Special CD-ROM (Part 1) | X68K | | | | | |
| Oh!X 2001 Spring Special CD-ROM | X68K | | | | | |
| Oha Suta Series 01: Zonapara
おはスタシリーズ０１ 象南波羅～ゾナパラ～ | KSITE | | Original |  | 536956 | |
| Oha Suta Series 02: Oha Ska!
おはスタシリーズ０２ おは スカ | KSITE | | Original | | 538714 | |
| Ohio Distinctive Software Vol. I | PC | | | | | |
| 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 | PC | | General Mills | | AM801R5 | |
| Oregano
Oregano: RISC OS Web Browser | ARCH | | Original | | | |
| The Oregon Trail: Classic Edition | PC | | SoftKey | | POT144EE-CD | |
 | Original Xbox Game Support: December 2005 (1.2)
Prise en charge des jeux Xbox d'origine: Décembre 2005 (1.2) | XBOX360 | | 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 | |
| Overwatch | PC | | Game of the Year Edition, Legendary Edition | | 73052010US, S7302210 | |
 | Overwatch | PC | | Origins Edition |      | | |
| Ozzie's World
オジィーズワールド | PC | | Original | | ASOW-71110 | |
| Owlboy (Game Disc) | PC | 0.0.6152.604 | IndieBox | | | |
| Operation Flashpoint: Cold War Crisis | PC | 1.0 | Original | | MOPFCDUS00 | |
| The Oregon Trail 3rd Edition: Pioneer Adventures | PC | 1.0 | DVD-ROM | | ORG811AE-DVD | |
 | Ostrov Nanda
Остров Нанда | PC | 1.000 | Original | | | |
| 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 | |
| Oil Tycoon | PC | 1.01 | Original | | | |
| The Orion Conspiracy | PC | 1.01 | Original | | | |
| Online Start-Up Disc 4.0: Broadband Only | PS2 | 1.02 | Bundled with PS2 | | PBPX 95248 … | |
| 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 | |
| Odnazhdy' v Chikago
Однажды в Чикаго | PC | 1.1.0.0 | Original | | | |
| Outpost 2: Divided Destiny | PC | 1.2.0.5 | Original | | | |
| The Oregon Trail | PC | 1.22 | Smart Saver | | ORT844AE-CD | |
| Oregon Trail II: 25th Anniversary Limited Edition | PC | 1.3 | Original, SoftKey | | #OTR744AE-CD | |
| Operation Flashpoint: Gold Upgrade | PC | 1.30 | Original | | MOFUCDUS00 | |
| Outpost | PC | 1.5 | Rerelease, Sierra Originals | | | |
| Operation Flashpoint: Resistance | PC | 1.75 | Original | | MOFRCDUS00 | |
| Outlaws (Disc 1) | PC | 2.0 | Rerelease | | 9511830 | |
| Outlaws (Disc 2) | PC | 2.0 | Rerelease | | 9511831 | |
| The Oregon Trail: Classic Edition | PC | 3.0.1 | SoftKey | | POT144CE-CD | |
| OnHand Sports Games / Sega Swirl Lite | PALM | PDA105-01 | OnHand Double Pack (Sports Games/Astrologer) | | PDA105-01 | |
| OnHand Complete Astrologer
OnHand Complete Astrologer: Horoscopes & More! | PALM | PDA108-01 | OnHand Double Pack (Sports Games/Astrologer) | | PDA108-01 | |
