- Origame
- Origami - Origami Art
- Origami Challenge
- Origami Math
- Origami.io
- Original Classic Snake
- Original Yatzy
- Orion - A Journey Beyond
- ORIS Reaction Race
- Orisinal Casanova
- OROBOROS
- Oscar's Bubbles
- Osmanlı Bilgi Yarışması Oyunu
- Osmo in Space
- Osmos
- Osolo
- Ostrich Among Us
- Ostrov Kostrov
- Osu Ninja Split
- Osushiya-san
- OTEDAMA
- Otherworldly Zombies
- Otter Evolution - Furry Sea Mutant Seal Breeding
- Otter Forest ~Idle Game~
- Otter Forest ~Idle Game~
- Otter Friends
- Otter Ocean - Scavenger Hunt
- Otter Polo
- Our Family Thief
- Our Spider Solitaire
- Out away!
- Out of Brakes - Endless Racer
- Out Of The Way TV
- Outage - A Memory Puzzle Game
- Outbreak ES
- OUTDODGE
- Outer Space Battle 2
- Outer Space Call Prank
- Outer Space Miracle Alien - Gogo Stack It Up Skyward Stacker
- Outfit Queen
- Outleap!
- Outpost Defender
- Outrace
- OutRush - Synthwave Action
- Outswipe: Survive The Traffic
- Ov e, Inch e - gushakir nkary
- Over Street: Traffic Racer
- Over The Bridge PRO
- Over the Clouds : Sheep Free ( Sleepy & Healing game )
- Over the Moon...
- Over The Net Beach Volley
- Over the Sea : Lite
- Over What Kill
- Overfed 3D
- Overjump Free
- Overkill Drill
- Overlaid
- Overlapi
- Overloaded!
- Overlord Ops: 3D FPS Game
- OverRapid
- OverTake
- Traffic Hot Driver Turn Racer
- Overworked: Ultimate Burnout
- OVIVO
- Owl Jump
- Own Coffee Shop: Idle Game
- Own Super Squad
- Ox Atan
- OX益智棋