Xbox - O
- Obscure
- Oddworld - Munch's Oddysee
- Oddworld - Stranger
- Oddworld - Stranger's Wrath
- Oddworld - Strangers Vergeltung
- Oddworld Stranger's Wrath
- Official X-Box Magazine Disk #22
- Official X-Box Magazine Disk #23
- Official X-Box Magazine Disk #27
- Official X-Box Magazine Disk #38
- Official X-Box Magazine Disk #45
- Open Season
- Operation Flashpoint - Cold War Crisis
- Operation Flashpoint - Elite
- Otogi
- Otogi - Myth of Demons
- Otogi 2
- Otogi 2 - Immortal Warriors
- Out Run 2
- Outlaw Chopper
- Outlaw Golf
- Outlaw Golf - 9 Holes of X-Mas
- Outlaw Golf 2
- Outlaw Golf Holiday Golf
- Outlaw Tennis
- Outlaw Volleyball
- Outlaw Volleyball - Spike or Die
- OutRun 2
- OutRun 2006
- OutRun 2006 - Coast 2 Coast
- Outrun 2006 - Coast to Coast
- OutRun2
- Over the Hedge