9: A: B: C: D: E: F: G: H: I: J: K: L: M: N: O: P: Q: R: S: T: U: V: W: X: Y: Z

• O.D.T. PC
• O.R.B. PC
• Oasis PC
• Obscure PC
• Obscure PlayStation 2
• Obscure Xbox
• Obsidian PC
• Oddworld Stranger's Wrath PlayStation 2
• Oddworld Stranger's Wrath Xbox
• Oddworld: Abe's Exoddus PC
• Oddworld: Abe's Exoddus PlayStation
• Oddworld: Abe's Oddysee PC
• Oddworld: Abe's Oddysee PlayStation
• Oddworld: Munch's Oddysee Game Boy Advance
• Oddworld: Munch's Oddysee Xbox
• Odium PC
• Odyssey: The Search for Ulysses PC
• Of Light and Darkness: The Prophecy PC
• Off Road Challenge Nintendo 64
• Off-Road Redneck Racing PC
• Offensive PC
• Officers PC
• Official Formula I Racing PC
• Ogre Battle PlayStation
• Ogre Battle 64 Nintendo 64
• Oha Star Dance Dance Revolution PlayStation
• Oil Tycoon PC
• Okage: Shadow King PlayStation 2
• Okami PlayStation 2
• Olympic Hockey '98 Nintendo 64
• Omega Boost PlayStation
• Omikron Dreamcast
• Omikron: The Nomad Soul PC
• Once Upon a Knight PC
• One N-Gage
• One (1997) PlayStation
• One Must Fall: 2097 PC
• One Must Fall: Battlegrounds PC
• One Piece Mansion PlayStation
• Oni Macintosh
• Oni PC
• Oni PC
• Oni PlayStation 2
• Onimusha 2: Samurai's Destiny PlayStation 2
• Onimusha 3: Demon Siege PlayStation 2
• Onimusha Blade Warriors PlayStation 2
• Onimusha Tactics Game Boy Advance
• Onimusha: Warlords PlayStation 2
• Online Striker PC
• Ooga Booga Dreamcast
• OP15: Rising Threat Mobile
• Open Kart PC
• Operation Air Assault PlayStation 2
• Operation Armored Liberty Game Boy Advance
• Operation Blockade PC
• Operation Flashpoint 2 PC
• Operation Flashpoint: Cold War Crisis PC
• Operation Flashpoint: Cold War Crisis Xbox
• Operation Flashpoint: Resistance PC
• Operation Shadow N-Gage
• Operation Steel Tide PC
• Operation Tiger Hunt PC
• Operation: Matriarchy PC
• Optimal Video Poker Mobile
• Or Die Trying (O.D.T.) PlayStation
• Orbz PC
• Orchid PlayStation 2
• Orchid Xbox
• Ore no Ryori PlayStation
• Oregon Trail Apple II
• Oriental Blue: Ao no Tengai Game Boy Advance
• Origin of the Species PC
• Original War PC
• Orphen: Scion of Sorcery PlayStation 2
• Ostrich Runner PC
• Otogi 2: Immortal Warriors Xbox
• Otogi: Myth of Demons Xbox
• Otto Matic Macintosh
• Otto Matic PC
• Out of the Park Baseball 4 PC
• Out of the Park Baseball 5 PC
• Out of the Park Baseball 6 PC
• Outburst PC
• Outcast PC
• Outcast 2: The Lost Paradise PlayStation 2
• Outdoor Life: Sportsman's Challenge PC
• Outlaw Golf GameCube
• Outlaw Golf PC
• Outlaw Golf Xbox
• Outlaw Golf 2 PlayStation 2
• Outlaw Golf 2 Xbox
• Outlaw Golf Holiday Golf Xbox
• Outlaw Tennis PlayStation 2
• Outlaw Tennis Xbox
• Outlaw Volleyball Xbox
• Outlaw Volleyball Remixed PlayStation 2
• Outlaws PC
• Outlive PC
• Outpost 2: Divided Destiny PC
• OutRun2 Xbox
• Outrun2 SP Arcade Games
• Outtrigger Dreamcast
• Outwars PC
• Over the Reich PC
• Overblood PlayStation
• Overblood 2 PlayStation
• Oz PlayStation 2
• Ozzy & Drix Game Boy Advance