| The Occupation (2019) | 98,073,324 | 5,277 |
| Occupy Mars (2023) | 8,710,762 | 6,410 |
| Occupy White Walls (2018) | 265,235 | 157 |
| Ocean Commander (2008) | 59,481 | 64 |
| Ocean Conqueror (1987) | 105,418 | 8 |
| Ocean Desolation (2024) | 4,796 | 17 |
| Ocean Drive Challenge (2012) | 5,563 | 19 |
| The Ocean Hunter (1998) | 2,195,763 | 262 |
| Ocean Is Home : Island Life Simulator (2022) | 2,826,370 | 181 |
| Ocean Keeper: Dome Survival (2024) | 63,490 | 105 |
| Ocean Man (2023) | 2,067,809 | 129 |
| Ocean of Vengeance (2025) | 0 | 0 |
| Ocean Planet (2024) | 640,364 | 36 |
| Ocean Punk (2023) | 324 | 5 |
| Ocean Trader (1995) | 3,079 | 6 |
| Ocean's Heart (2021) | 1,987,564 | 2,108 |
| Oceanarium World (2024) | 1,259 | 1 |
| Oceancatch (2022) | 0 | 0 |
| OceanCraft (2021) | 3,701,680 | 97 |
| Oceaneers (2026) | 29,298 | 10 |
| Oceanhorn 2: Knights of the Lost Realm (2019) | 19,474,105 | 4,632 |
| Oceanhorn: Chronos Dungeon (2021) | 331,689 | 345 |
| Oceanhorn: Monster of Uncharted Seas (2013) | 27,002,864 | 9,478 |
| Oceanwork (2021) | 295,549 | 87 |
| Ocelot Sunrise (2023) | 17,813 | 40 |
| Ochitsubaki (2021) | 78 | 2 |
| Ocnus Theory (2023) | 464 | 14 |
| OCO (2021) | 334,558 | 109 |
| OctaFight (2020) | 2,619,301 | 62 |
| Octagon (2013) | 559,660 | 232 |
| Octahedron (2018) | 972,570 | 211 |
| Octane Remix (2023) | 457 | 14 |
| Octane100 (2026) | 0 | 0 |
| Octapolis (1987) | 9,043 | 11 |
| Octavio Camacho (2023) | 0 | 0 |
| Octo Vinctum: Saga of the Galactic Stardom War (2022) | 0 | 0 |
| Octo's Balloon Challenge (2024) | 553 | 2 |
| October Night Games (2020) | 265,260 | 38 |
| Octodad (2010) | 362,064,619 | 5,003 |
| Octodad: Dadliest Catch (2014) | 420,224,019 | 12,175 |
| OctoFurry (2020) | 3,393 | 3 |
| Octogeddon (2018) | 292,641,742 | 1,492 |
| Octohill Ski Tycoon (2025) | 0 | 0 |
| Octomania (2007) | 30,755 | 61 |
| OctoMaze (2022) | 4,296 | 40 |
| Octopath Traveler (2018) | 165,382,165 | 102,072 |
| OCTOPATH TRAVELER 0 (2025) | 43,760 | 126 |
| Octopath Traveler II (2023) | 50,048,753 | 62,310 |
| Octopath Traveler: Champions of the Continent (2020) | 15,852,114 | 10,398 |
| Octopede (2011) | 169 | 1 |
| OCTOPinbs (2026) | 280,415 | 41 |
| OCTOPTICOM (2018) | 1,404 | 27 |
| OCTOPTICOM 3D (2024) | 0 | 0 |
| Octopus City Blues (2025) | 7,840 | 41 |
| Octopus Invasion (2025) | 0 | 0 |
| Octoshield VR (2016) | 0 | 0 |
| Ocular Deprivation (2022) | 124 | 7 |
| Oda Nobunaga Den (1998) | 128,373 | 260 |
| Odallus: The Dark Call (2015) | 1,884,034 | 1,208 |
| Odama (2006) | 669,255 | 193 |
| Odania Sports Arena (2022) | 164 | 5 |
| Odd Island (2018) | 0 | 0 |
| Odd Realm (2019) | 1,543,519 | 430 |
| Odd Remedy (2024) | 960,048 | 27 |
| Odd Sequence (2024) | 312 | 2 |
| ODDADA (2024) | 24,818 | 49 |
| Oddballz (1996) | 28,775 | 16 |
| Oddinary Highway (2021) | 299 | 9 |
| Oddity Girls: Virtual World (2020) | 1,068 | 9 |
| Oddly Enough: Pied Piper (2011) | 9,817 | 9 |
| Oddmar (2018) | 3,512,661 | 2,988 |
| ODDRooM (2025) | 0 | 0 |
| Oddsparks: An Automation Adventure (2024) | 2,293,231 | 2,688 |
| Oddventure (2022) | 178,630 | 144 |
| Oddworld Adventures (1998) | 76,436 | 154 |
