| Game Name | System |
|---|
| Ocean-240 with fdd | MAME |
| Ochainu Kururin (J)(Caravan) | GBA |
| Ochainu no Bouken Jima (J)(sUppLeX) | GBA |
| Ochainu no Daibouken (J)(6rz) | NDS |
| Ochaken No Heya (J)(Rising Sun) | GBA |
| Ochaken no Daibouken 2 - Yume Ippai no Omochabako (J)(EXiMiUS) | NDS |
| Ochaken no Heya DS (J)(WRG) | NDS |
| Ochaken no Heya DS 2 (J)(WRG) | NDS |
| Ochaken no Heya DS 2 (v01) (JP)(High Road) | NDS |
| Ochaken no Heya DS 3 (J)(Independent) | NDS |
| Ochaken no Heya DS 3 (v01) (JP)(High Road) | NDS |
| Ochaken no Heya DS 4 - Ochaken Land de Hotto Shiyo (JP)(Caravan) | NDS |
| Ochaken no Yumebouken (J)(Caravan) | GBA |
| Oci | Atari 800 |
| Octagon (19xx)(Budgie Budget Software) | ZX Spectrum Z80 |
| Octagon (19xx)(Budgie Budget Software)[a] | ZX Spectrum Z80 |
| Octagon Squad, The (1986)(Mastertronic) | ZX Spectrum (TAP) |
| Octalyser, The (19xx)(Alan F. Blade)(SW) | Atari ST |
| Octan (1987)(Silverbird) | ZX Spectrum (TAP) |
| Octan (1987)(Silverbird) | ZX Spectrum Z80 |
| Octapolis (E) | C64 Tapes |
| Octipede (19xx)(-)(128k) | ZX Spectrum Z80 |
| Octoplex (E) | C64 Tapes |
| Octoplex (UK) (1989) | CPC |
| Octoplex (UK) (1989) [t1] | CPC |
| Octopus (1999)(Andy Kavanaugh) | ZX Spectrum Z80 |
| Octopus (Nova) (MPU4) | MAME |
| Oczko | Atari 800 |
| Oda Nobunaga - Haou no Gundan (Japan) | SNES |
| Odama | GCN |
| Odama (Europe) (En,Fr,De,Es,It) | GCN |
| Odd Ball (1987)(The Power House) | ZX Spectrum Z80 |
| Odd Ball (1987)(The Power House)[a] | ZX Spectrum Z80 |
| Odd Job Eddie (1985)(Amstrad)(128k) | ZX Spectrum Z80 |
| Odd Job Eddie (1985)(Strobe) | ZX Spectrum Z80 |
| Odd_Man_Out_Plurals | Atari 800 |
| Oddball (1995)(Amnesia) | Archimedes |
| Oddjob - The Disc Utility Package (F) (1985) | CPC |
| Oddjob - The Disc Utility Package (S) (1985) | CPC |
| Oddjob - The Disc Utility Package (UK) (1985) | CPC |
| Odds On (Barcrest) (MPU3) | MAME |
| Oddworld - Abe's Exoddus (E) (Disc 1) | PSX |
| Oddworld - Abe's Exoddus (E) (Disc 2) | PSX |
| Oddworld - Abe's Exoddus (S) (Disc 1) | PSX |
| Oddworld - Abe's Exoddus (S) (Disc 2) | PSX |
| Oddworld - Abe's Exoddus (USA) | PSX2PSP |
| Oddworld - Abe's Exoddus [NTSC-U] [Disc1of2] | PSX |
| Oddworld - Abe's Exoddus [NTSC-U] [Disc2of2] | PSX |
| Oddworld - Abe's Oddysee (Demo) (E) | PSX |
| Oddworld - Abe's Oddysee (E) | PSX |
| Oddworld - Abe's Oddysee (S) | PSX |
| Oddworld - Abe's Oddysee (USA) | PSX2PSP |
| Oddworld - Abe's Oddysee [NTSC-U] | PSX |
| Oddworld - Abe's Oddysee [U] (v1.0) | PSX |
| Oddworld - Munch's Oddysee (G)(Rising Sun) | GBA |
| Oddworld - Munch's Oddysee (U)(Rising Sun) | GBA |
| Oddworld Adventures (USA, Europe) | GB |
| Oddworld Adventures II (USA, Europe) (En,Fr,De,Es,It) | GBC |
| Odekake Lester - Lelele no Le (Japan) | SNES |
| Odell Lake (UE) | C64 PP |
| Odenkun - Tanoshii Oden Mura (J)(Caravan) | NDS |
| Odeon Twister 2 (v202.19) | MAME |
| Odetake Chocobo (1999)(Square)[Final Fantasy 8] | Pocketstation |
| Odieu's Quest for the Magic Flingshot | Atari 800 |
| Odieus_Quest_for_the_Magic_Flingshot_CTH_Enterprises | Atari 800 |
| Odin | MAME |
| Odin (19xx)(Odesta)[k-file] | Atari 800 |
| Odin De Luxe | MAME |
| Odin Sphere (Europe) (En,Ja,Fr,De,Es,It) | PS2 |
| Odin Sphere (USA) (En,Ja) | PS2 |
| Odisea (1990)(Juano Pueblo Soft)(Sp)[Part 1 of 2] | ZX Spectrum Z80 |
| Odisea (1990)(Juano Pueblo Soft)(Sp)[Part 2 of 2] | ZX Spectrum Z80 |
| Odisea Paris-Dakar | MAME |
| Odoru Daisousasen The Game - Sensuikan ni Sennyuu Seyo! (J) | NDS |
| Odwracanka (1986)(L.P.)(pl) | Atari 800 |
| Odwracanka (ArSoft) | Atari 800 |
| Odyssee (19xx)(-)(De) | ZX Spectrum Z80 |
| Odysseus | Atari 800 |
| Odysseus - Trojan Warrior (E) | C64 Tapes |
| Odyssey (E) | C64 Tapes |
| Odyssey (UE) | C64 PP |
| Odyssey (UK) (1994) (PD) (Disk 1 of 2) | CPC |
| Odyssey (UK) (1994) (PD) (Disk 2 of 2) | CPC |
| Odyssey 2 | MAME |
| Odyssey 3 Command Center (prototype) | MAME |
| Odyssey I (1983)(Perfection Software) | ZX Spectrum (TAP) |
| Odyssey Of Hope, The (1984)(Martech Games) | ZX Spectrum Z80 |
| Odyssey, The Compleat Adventure (1980)(Synergistic Software) | Apple2 |
| Odyssey, The Compleat Adventure (1980)(Synergistic Software)[b] | Apple2 |
| Oedo Fight (Japan Bloodshed Ver.) | MAME |
| Oei (19xx)(Oei)(128k)(UNK-LANG) | ZX Spectrum Z80 |
| Oeil De Set, L' (F) (1987) (Disk 1 of 2) | CPC |
| Oeil De Set, L' (F) (1987) (Disk 2 of 2) | CPC |
| Oeka Kids - Anpanman no Hiragana Daisuki (Japan) | NES |
| Oeka Kids - Anpanman to Oekaki Shiyou!! (Japan) | NES |
| Oekaki Logic (Japan) (NP) | SNES |
| Oekaki Logic 2 (Japan) (NP) | SNES |
| Oekaki Puzzle | NGPC |
| Oekaki Puzzle Battle Vol.1 - Yuusha-Oh GaoGaiGar Version (J)(Mode 7) | NDS |
| Oekopoly | Atari 800 |
