| Oppai no Ouja 48 | r97903 | 2026-04-21 |
| Oppaidius: Desert Island! - Deluxe Edition | r71974 | 2026-04-21 |
| Oppaidius: Desert Island! - Deluxe Topless Cover Limited Edition | r71975 | 2026-04-21 |
| Oppaidius: Desert Island! - Demo | r77567 | 2026-05-12 |
| Oppaidius: Desert Island! - Download Edition | r71972 | 2026-04-21 |
| Oppaidius: Desert Island! - Physical Edition | r71973 | 2026-04-21 |
| Oppaidius: Summer Trouble! - Deluxe Edition | r54019 | 2026-04-21 |
| Oppaidius: Summer Trouble! - Demo v1.0 | r54015 | 2026-04-21 |
| Oppaidius: Summer Trouble! - Demo v1.1 | r54016 | 2026-04-21 |
| Oppaidius: Summer Trouble! - Download Edition | r54017 | 2026-04-21 |
| Oppaidius: Summer Trouble! - Physical Edition | r54018 | 2026-04-21 |
| Oppaidius: Tropical Cruise! | r66996 | 2026-04-21 |
| Oppenheim no Kojou | r81628 | 2026-05-15 |
| Opportunity: A Sugar Baby Story | r88082 | 2026-04-21 |
| Opportunity: A Sugar Baby Story - Chapter 1 | r78085 | 2026-05-15 |
| Opportunity: A Sugar Baby Story - Chapter 2 | r88080 | 2026-05-15 |
| Opportunity: A Sugar Baby Story - Chapter 3 | r88081 | 2026-05-15 |
| Opportunity: A Sugar Baby Story - Chapter 4 | r94400 | 2026-05-15 |
| Opportunity: A Sugar Baby Story - Chapter 5 | r103663 | 2026-04-21 |
| Optimal Solution | r123261 | 2026-04-21 |
| Oral Lessons With Chii-chan | r61202 | 2026-04-21 |
| Oral Lessons With Chii-chan | r120860 | 2026-04-21 |
| Oral Lessons With Chii-chan - GOG Edition | r135732 | 2026-05-16 |
| Oral Lessons With Chii-chan ♥ | r81332 | 2026-04-21 |
| Orange Blossoms | r124811 | 2026-04-21 |
| Orange Blossoms - Demo | r107397 | 2026-04-21 |
| Orange Couch | r45103 | 2026-04-21 |
| Orange Couch | r28617 | 2026-04-21 |
| Orange Heart | r39979 | 2026-04-21 |
| Orange Honey ~Boku wa Kimi ni Koishiteru~ Regular Edition | r15782 | 2026-05-10 |
| Orange Marmalade | r16716 | 2026-04-21 |
| Orange Marmalade - Download Edition | r16731 | 2026-04-21 |
| Orange Marmalade: Haikyuu Otome Game | r103905 | 2026-05-14 |
| Orange Memories | r9275 | 2026-04-21 |
| Orange Pocket | r490 | 2026-05-06 |
| Orange Pocket -コルネット- 初回限定版 | r488 | 2026-04-21 |
| Orange Pocket -コルネット- 通常版 | r3335 | 2026-04-21 |
| Orange Pocket -リュート- 初回限定版 | r487 | 2026-04-21 |
| Orange Pocket -リュート- 通常版 | r3336 | 2026-04-21 |
| Orange Smash! v0.4 | r127934 | 2026-04-21 |
| Orange Smash! v0.5 | r136058 | 2026-04-21 |
| Orange Trainer | r62201 | 2026-04-21 |
| OrangePocket -オレンジポケット- 初回版 | r486 | 2026-04-21 |
| OrangePocket Ver1.10 for Win10 | r71636 | 2026-04-21 |
| Orangepeel, Onionskin | r143440 | 2026-04-21 |
| Oratio | r29120 | 2026-04-21 |
| Oratio体験版 | r29121 | 2026-04-21 |
| Oratorio ~Umi yori Aoi Natsu no Kanata de~ Sabun Fairu 03 no Dīeru | r144925 | 2026-05-11 |
| Oratorio ～約束～ | r12268 | 2026-04-21 |
| Orbital Paladin Melchior Y | r62443 | 2026-04-21 |