| Oddworld: Abe's Exoddus (1998) | 12,572,586 | 6,003 |
| Oddworld: Abe's Oddysee (1997) | 36,878,846 | 8,822 |
| Oddworld: Munch's Oddysee (2001) | 8,687,319 | 2,541 |
| Oddworld: New 'n' Tasty! (2016) | 27,054,366 | 9,974 |
| Oddworld: Soulstorm (2021) | 69,115,097 | 15,802 |
| Oddworld: Stranger's Wrath (2005) | 17,080,333 | 6,093 |
| Oddyssey: Your Space, Your Way (2023) | 340,556 | 111 |
| Odell Lake (1986) | 79,015 | 31 |
| Odile: Black Duckling Tale (2025) | 0 | 0 |
| Odin Sphere (2007) | 6,928,155 | 7,647 |
| Odin Sphere Leifthrasir (2016) | 10,772,268 | 20,388 |
| Odium (2022) | 130,316 | 81 |
| Odiumfloreo (2025) | 0 | 0 |
| Odysseus Kosmos and his Robot Quest (2018) | 247,167 | 162 |
| Odyssey - The Story of Science (2017) | 1,868 | 10 |
| The Odyssey of Commander Cookie (2025) | 0 | 0 |
| Odyssey of Dremid'ir (2024) | 27 | 4 |
| The Odyssey of the Mammoth (2022) | 1,174,178 | 259 |
| Odyssey to the Frozen Legion (2025) | 0 | 0 |
| Odyssey: The Compleat Apventure (1980) | 9,440 | 6 |
| Odyssey: The Deep Space Expedition (2019) | 328 | 1 |
| Odyssey: The Search for Ulysses (2000) | 23,546 | 37 |
| Oedipus Dating Sim (2018) | 34 | 1 |
| Oedipus/Antigone (2024) | 0 | 0 |
| Of Ash and Steel (2025) | 3,425,559 | 2,761 |
| Of Bird and Cage (2021) | 287,951 | 432 |
| Of Blades & Tails (2022) | 435,634 | 293 |
| Of Crowns & Chains (2025) | 0 | 0 |
| Of Gods and Men: The Daybreak Empire (2018) | 6,398 | 18 |
| Of Guards And Thieves (2014) | 1,250,975 | 352 |
| Of Ink and Silver (2025) | 0 | 0 |
| Of Kings and Men (2016) | 3,345,470 | 285 |
| Of Lies and Rain (2025) | 379,435 | 305 |
| Of Light and Darkness: The Prophecy (1998) | 6,054 | 11 |
| Of Love And Sorrow (2016) | 58 | 1 |
| OF MICE AND SAND -REVISED (2018) | 17,619 | 116 |
| Of Mice and Sand: Revised (2017) | 33,572 | 88 |
| Of Orcs and Men (2012) | 6,200,377 | 3,079 |
| of pawns & kings (2023) | 936 | 5 |
| Of Ships & Scoundrels (2019) | 21,355 | 26 |
| Off (2008) | 3,864,668 | 1,304 |
| Off Course ELEMENTS of SPACE (2024) | 9 | 2 |
| Off Road (2008) | 608,692,489 | 29,578 |
| Off Road Challenge (1997) | 3,452,941 | 540 |
| Off Shore Warrior (1988) | 11,179 | 16 |
| Off The Record: Liberty Stone (2015) | 44,845 | 62 |
| Off The Record: The Art of Deception (2015) | 46,642 | 78 |
| Off the Record: The Final Interview (2015) | 32,486 | 57 |
| Off the Record: The Italian Affair (2014) | 44,608 | 103 |
| Off the Record: The Linden Shades (2013) | 28,986 | 43 |
| Off The Road Unleashed (2021) | 13,411,292 | 1,317 |
| Off the Wall (1991) | 1,540,583 | 220 |
| Off-Road Drive (2011) | 22,528,002 | 1,942 |
| Off-Road Paradise: Trial 4x4 (2017) | 627,824 | 53 |
| Off-Road Redneck Racing (2001) | 37,068 | 45 |
| Off-Road Super Racing (2016) | 194,287 | 39 |
| Off-Road Velociraptor Safari (2008) | 35,988 | 19 |
| Off-World Interceptor (1994) | 116,889 | 224 |
| Offendron Warrior (2018) | 130 | 6 |
| Offensive Combat (2017) | 1,010,801 | 272 |
| Offensive Dimensions (2017) | 23 | 1 |
| OFFERING APP (2023) | 127,496 | 59 |
| Office After Hours (2025) | 985,466 | 124 |
| Office Assistant (2025) | 0 | 0 |
| Office Battle (2015) | 23,789,027 | 114 |
| Office Disorders (2010) | 205 | 2 |
| Office Fight (2024) | 53,387 | 57 |
| Office Girls and Games (2023) | 320 | 7 |
| Office Management 101 (2022) | 68,447 | 62 |
| Office Nightmare Chapter 1 Alpha (2024) | 167 | 1 |
| Office of Interstellar Production (2025) | 0 | 0 |
| Office Outbreak Savior (2025) | 0 | 0 |
| Office Overloaded (2025) | 42 | 1 |
| The Office Quest (2018) | 13,333,028 | 650 |
| Office Rivals (2025) | 0 | 0 |
