- Offroad Race
- Offroad Truck Dash
- OG Switch
- Ogg World
- OGole - Party game
- Oh C.R.A.P.!
- Oh Dear Dead Again
- Oh Duck
- Oh God!
- Oh Hell Online
- Oh No! Ninjas!
- ああ!私のバナナ
- Oh! My Egg
- OH! Shapes: A Chain Match Game
- Ohana Island
- きのこうまー
- Oil Barron
- Oil Hunt
- Oil Hunt 2 - Birthday Party
- Oil Leak
- 数字による油絵のアートの色
- Oil Plumber City Plus
- Oil Tanker Transporter Cargo
- Oil Well Drilling
- Oil Well Drilling
- Oil Wrestling
- OinkPop Godot
- OinkPop Scratch
- Oinky Doink
- OK Tap
- OK! Bird - Wing Up
- Okay or Boomer!
- Okey Muhabbet
- Olan And Butterflies
- Old Brick Machine Game
- Old City Pub : Hidden Games
- オールドフレンズ ~ 犬のゲーム
- Old Galaxian
- Old HK Lite
- Old HK PhotoHut
- オールドマン釣り - 狩猟&時間に対する魚のレースをキャッチ
- おじたま~奇妙なクリッカー系放置ゲーム~
- Old School Test Drive
- Old Skull Fighters: Bone-Chilling
- Oldschool Blocks
- OLDTV
- Ole Bunny
- Olimpo vs Slimes
- OLLECT - Pair Matching Game
- Ollie Cats
- Ollie Pop - 8Bit Retro Skateboarding
- OLO Loco
- Olympus Dash
- Om Nom Nom Seonkyoung Longest
- Om Nom: Merge
- Om Nom: Run
- Omega Run
- 超キモイ!虫潰し
- On Desert Island
- On fire : basketball shots
- On Point Mecha
- On Point!
- On The Enchanted Forest
- On The Wrong Way Run
- Once Upon a Tower
- OnClick!
- One Button Travel
- One By One - Math Game
- One Dice
- One Escape!