Oh! Hajiki! (19xx)(Maru)
Oh! Pai (199x)(Silky's)(Disk 1 of 5)(Disk A)
Oh! Pai (199x)(Silky's)(Disk 3 of 5)(Disk C)
Oh! Pai (199x)(Silky's)(Disk 2 of 5)(Disk B)
Oh! Pai (199x)(Silky's)(Disk 4 of 5)(Disk D)
Oh! Pai (199x)(Silky's)(Disk 5 of 5)(Disk E)
Ohootsuku Ni Kiyu (19xx)(Login)
Okumanchouja (19xx)(Cosmos Computer)
Ooedo Hanseiki (19xx)(Panther Software)(Disk 2 of 3)
Ooedo Hanseiki (19xx)(Panther Software)(Disk 1 of 3)
Ooedo Hanseiki (19xx)(Panther Software)(Disk 3 of 3)
Ora Ora Ball (1995)(Ora Soft)(Disk 2 of 2)
Ora Ora Ball (1995)(Ora Soft)(Disk 1 of 2)
Ora-Shoot (1996)(Ora Soft)(Disk 1 of 2)
Ora-Shoot (1996)(Ora Soft)(Disk 2 of 2)
Ora-Shoot (1996)(Ora Soft)(Disk 2 of 2)[a]
Orange Iro No Biyaku (1989)(System House Oh!)
Original Games (2001)(Tau Software)
Otaku Dama (1999)(Mitsuky)
Otaku Dama (1999)(Mitsuky)[h]
Ougon No Buta (19xx)(Shoujo)
Ougon No Rashinban (1989)(Riverhill Soft)(Disk 2 of 3)(Game)
Ougon No Rashinban (1989)(Riverhill Soft)(Disk 3 of 3)(Data)
Ougon No Rashinban (1989)(Riverhill Soft)(Disk 1 of 3)(System)
Overtake (1992)(Zoom)(Disk 1 of 6)(System)
Overtake (1992)(Zoom)(Disk 2 of 6)(Data A)
Overtake (1992)(Zoom)(Disk 6 of 6)(Opening 2)
Overtake (1992)(Zoom)(Disk 5 of 6)(Opening 1)
Overtake (1992)(Zoom)(Disk 3 of 6)(Data B)
Overtake (1992)(Zoom)(Disk 4 of 6)(Data C)
