- O & X for Watch
- O & X: Noughts and Crosses
- O is for Obliteration
- O X大師
- O X Multi
- O-ZONE - Protect the Earth
- Oak Island Treasure Hunt
- Obliteracy
- 佔領部落
- Octav
- OctoHits
- Octopus Evolution
- Odd Color - Test Your Color Vision
- Odds Are for Messages
- 千秋辭國際版
- OEGames Land Navigation
- Off-Road Transport Trailer
- Office Story
- Office Thief - Escape Puzzle
- Officer's Skat
- OffRoad Runway Construction 18
- OG Switch
- OGS Notifications
- OGS Notify
- 大江戶物語
- OH~! My Office - Boss Sim Game
- Oil Barron
- Oil Capitalist - Addicting Clicker Game To Become A Rich Billionaire Tycoon
- Oil Tycoon 2: Idle Empire Game
- Oil Tycoon: idle gas simulator
- Oil Tycoon: Idle Empire Games
- Oil, Inc. - Idle Clicker
- Okey Arataş
- Okhlos 哲學家
- Old-School Snafu
- Olimpo vs Slimes
- Olympus Defense TD. Fury Rome Gods Rising In Divine Vengeance
- Olympus Rising:英雄防禦
- Omar Sharif Bridge Card Game
- 星環爭霸戰 (Omega Force)
- Omi Sri Lankan Card Game
- One Block Sudoku
- 一筆書
- One Line Drawing - Duel
- One Night at Flumpty's
- One Night at Flumpty's 2
- One Night at Flumpty's 3
- 图形数独: 一笔连成一个世界
- One Plate!
- One Touch Line Draw Game
- OneBit Adventure
- Onet Classic - Connect Mahjong
- Onet Connect 2016
- Onet Connect Animal Legend
- OneUp: Tiger Edition
- Online Checkers LiveGames
- Online Checkers With Friends
- Online Chess LiveGames
- Online Preference LiveGames
- Online Zoo Builder
- Only Flaps And Horses
- Opacha-mda
- Opdoku = Calcudoku + Mathdoku
- 全部點亮
- Operasyon ATAK
- Operasyon: ANKA
- Operation Ares - A Revolution on Mars! Recruit Spies, Complete Missions, & Gain Independence
- Operation Optics
- Operation: New Earth
- Optical Inquisitor 17+
- OptiFlight
- 球球英雄:PVP塔防
- Orbeez – O resgate dos Woozers
- 星际守护者
- Orbit Shots