| OlliOlli2: Welcome to Olliwood (2015) | 4,247,942 | 750 |
| OlliOlli: Switch Stance (2016) | 79,115 | 40 |
| Olmang Jolmang Paradise (1995) | 2,784 | 12 |
| OloFight (1999) | 6,336 | 3 |
| Olorun: Theocracy (2018) | 0 | 0 |
| Olympia Soiree (2020) | 0 | 0 |
| Olympia Soirée (2021) | 9,831,960 | 614 |
| Olympia Soiree - Nintendo Switch (2020) | 0 | 0 |
| Olympic Basketball (2019) | 98,070 | 29 |
| Olympic Decathlon (1980) | 13,635 | 17 |
| Olympic Games Tokyo 2020 - The Official Video Game (2019) | 53,354,576 | 3,134 |
| Olympic Games: Atlanta 1996 (1996) | 4,841 | 10 |
| Olympic Gold (1992) | 867,072 | 203 |
| Olympic Hockey '98 (1998) | 83,571 | 100 |
| Olympic Soccer (1996) | 63,810 | 157 |
| Olympic Summer Games (1996) | 441,789 | 289 |
| Om Nom: Run (2020) | 64,744,916 | 10,053 |
| OM6N (2017) | 169 | 4 |
| Omae Wa Mou Shindeiru (2018) | 9,654,262 | 368 |
| Omar Sharif on Bridge (1992) | 4,671 | 4 |
| Omega (1989) | 88,383 | 78 |
| Omega Boost (1999) | 1,221,313 | 526 |
| Omega Crafter (2024) | 731,482 | 1,308 |
| Omega Enfo Bla (2010) | 1,387 | 2 |
| Omega Extinction (2017) | 0 | 0 |
| Omega Fighter (1989) | 96,927 | 227 |
| Omega Five (2008) | 89,137 | 94 |
| Omega Labyrinth Life (2019) | 1,425,870 | 547 |
| Omega Mouse Zero (2024) | 8,709 | 10 |
| OMEGA PATTERN - VISUAL NOVEL (2017) | 353 | 5 |
| Omega Quintet (2014) | 2,580,692 | 5,114 |
| Omega Race (1981) | 107,602 | 157 |
| Omega Run (1984) | 7,327 | 4 |
| The Omega Stone (2003) | 27,616 | 14 |
| Omega Strike (2017) | 805,757 | 693 |
| Omega Strikers (2023) | 10,523,392 | 7,210 |
| Omega Warp (2023) | 878 | 22 |
| Omelet You Cook (2025) | 148,939 | 16 |
| Omen Exitio: Hunger (2024) | 514 | 11 |
| Omen Exitio: Plague (2018) | 43,069 | 184 |
| Omen of Sorrow (2018) | 2,235,271 | 1,639 |
| Omensight (2018) | 1,010,553 | 2,062 |
| Omerta: City of Gangsters (2013) | 3,506,597 | 2,024 |
| Ometron (1983) | 265 | 1 |
| OMFG: One Million Fatal Guns (2021) | 17,132 | 134 |
| OMG Words (2025) | 17,342 | 12 |
| OMG! Not Another Isekai (2023) | 0 | 0 |
| OMG-Z (2011) | 46,817 | 52 |
| Omi Oh My AI (2022) | 56 | 1 |
| Omikron: The Nomad Soul (1999) | 12,419,699 | 1,586 |
| Ominoflux (2024) | 0 | 0 |
| Ominous Horizons: A Paladin's Calling (2001) | 15,255 | 16 |
| Ominous Objects: Family Portrait (2014) | 28,785 | 69 |
| Ominous Objects: Lumina Camera (2016) | 11,913 | 70 |
| Ominous Objects: Phantom Reflection (2015) | 48,750 | 89 |
| Ominous Objects: The Cursed Guards (2017) | 23,769 | 45 |
| Ominous Objects: Trail of Time (2015) | 32,867 | 44 |
| Ominous Tales: The Forsaken Isle (2017) | 9,913 | 53 |
| Omni Axes (2023) | 0 | 1 |
| Omnibion War (2020) | 21,311 | 32 |
| Omniblast (2021) | 0 | 1 |
| Omnibullet (2023) | 21,979 | 7 |
| OmniBus (2016) | 23,109,706 | 1,074 |
| Omnicube (2018) | 2,605 | 6 |
| OmniFootman (2019) | 66,243 | 49 |
| Omnigon (2023) | 2,393 | 1 |
| Omnimancer (2024) | 1 | 1 |
| OMNIMUS (2019) | 3,898 | 21 |
| Omnipresent (2015) | 73,036 | 10 |
| Omno (2021) | 4,787,991 | 5,677 |
| Omoide ni Kawaru Kimi (2002) | 1,223 | 9 |
| Omori (2020) | 296,601,882 | 61,609 |
| OMSI 2 (2013) | 242,914,052 | 69,384 |
| OMSI: The Bus Simulator (2011) | 97,884,832 | 8,555 |
| Omurice Next Time (2024) | 118 | 4 |
