Similar to ボンバーマンコレクション

Oninaki

Onimusha

Bail or Jail

Off (video game)

Observer (video game)

Operation Flashpoint: Cold War Crisis

Operation Flashpoint: Dragon Rising

Half-Life: Opposing Force

Omoide ni Kawaru Kimi: Memories Off

Omori (video game)

Ori and the Will of the Wisps

Ori and the Blind Forest

We Without Wings

The Orange Box

Only Up!

CRSED: F.O.A.D.