- O & X for Watch
- O & X: Noughts and Crosses
- O Dever Me Chama
- The Amazing Little Circus
- O is for Obliteration
- O Jardim da Silvana
- O Luga O Le Motu
- O Mundo de Augusto
- O papagaio que não sabia falar
- What is it? - Quiz Game
- O Show da Luna! Vamos Colorir
- O stříbrném pírku
- O X Master
- O X Multi
- O$P$ (Owe Money Pay Money)
- O'zapft is! - Oktoberfest Labyrinth 2016
- O-ZONE - Protect the Earth
- O2Jam - Music & Game
- Oak Creek GC
- Oak Creek Golf Club
- Oak Island Treasure Hunt
- Oakley's Adventure
- Oasis Poker
- Oasis!
- Obake Puzzle
- Obake-Touch
- Obama 2022
- Obama Run: 2024
- Obduction
- Obesenec - Slovenský Hangman
- Obey Me! - Anime Otome Sim -
- OBIO
- Object Hunt
- Object X
- Objectifs : Jeu de Cartes
- Objects Learning Game
- Objects order: memory game
- Obliteracy
- Objects order: memory game
- Obliteracy
- Oblivion – The Black Hole – Mission Oblivion
- Observa
- Obsession
- Obstacle Ball pool
- Obstacle Course Car Parking
- Obstacle Of Monkey
- Obstalique
- OBVERSION
- Oby's Barrel Travel
- Oběšenec - Český Hangman
- OC Penguin
- Occi-Expert
- Occidental Heroes
- Occult Crime Police
- Occult: Satanic interrogation
- Occultus