series starting with o
Odeon Twister
Odeon Twister (v1.4)
| Name | odeontw |
| Mfr | CD Express |
| Year | 1998 |
| Genre | Compilation |
| Players | N/A |
| Status | preliminary |
| DLs | 8 |
Odeon Twister 2 (v202.19)
| Name | odeontw2 |
| Mfr | CD Express |
| Year | 1998 |
| Genre | Mature |
| Players | N/A |
| Status | preliminary |
| DLs | 15 |
Off Road
Off Road Challenge (v1.63)
Offroad Thunder
| Name | offrthnd |
| Mfr | Midway Games |
| Year | 2000 |
| Genre | Driving |
| Players | 1 |
| Status | preliminary |
| DLs | 37 |
Ojanko Yakata
Ojanko Yakata 2bankan (Japan)
| Name | ojanko2 |
| Mfr | V-System Co. |
| Year | 1987 |
| Genre | Mature |
| Players | 1 |
| Status | good |
| DLs | 6 |
Ojanko High School (Japan)
| Name | ojankohs |
| Mfr | V-System Co. |
| Year | 1988 |
| Genre | Mature |
| Players | 1 |
| Status | good |
| DLs | 8 |
Ojanko Yakata (Japan)
| Name | ojankoy |
| Mfr | V-System Co. |
| Year | 1986 |
| Genre | Mature |
| Players | 1 |
| Status | good |
| DLs | 5 |
Operation Wolf
Operation Tiger (Ver 2.14 O)
Operation Tiger Second Mission (Ver 2.02 J)
Operation Wolf (World, rev 2, set 1)
| Name | opwolf |
| Mfr | Taito Corporation Japan |
| Year | 1987 |
| Genre | Gun |
| Players | 1 |
| Status | imperfect |
| DLs | 107 |
Operation Wolf 3 (World)
| Name | opwolf3 |
| Mfr | Taito Corporation Japan |
| Year | 1994 |
| Genre | Gun |
| Players | 2 |
| Status | good |
| DLs | 213 |
Operation Thunderbolt (World, rev 1)
| Name | othunder |
| Mfr | Taito Corporation Japan |
| Year | 1988 |
| Genre | Gun |
| Players | 2 |
| Status | good |
| DLs | 66 |
Oriental Legend
Oriental Legend Super / Xiyou Shi E Zhuan Super (ver. 101, Korean Board)
| Name | olds |
| Mfr | IGS |
| Year | 1998 |
| Genre | Beat-'Em-Up |
| Players | 4 |
| Status | preliminary |
| DLs | 166 |
Oriental Legend 2 (Korea) / Xiyou Shi E Zhuan Qunmoluanwu (World, China, Japan, Hong Kong, Taiwan) (ver. 205) [Oriental Ex]
| Name | oldsplus |
| Mfr | IGS |
| Year | 2004 |
| Genre | Beat-'Em-Up |
| Players | 4 |
| Status | preliminary |
| DLs | 77 |
Oriental Legend 2 (V104, Oversea)
| Name | orleg2 |
| Mfr | IGS |
| Year | 2007 |
| Genre | Beat-'Em-Up |
| Players | 4 |
| Status | good |
| DLs | 753 |
Oriental Legend / Xiyou Shi E Zhuan (ver. 126)
| Name | orlegend |
| Mfr | IGS |
| Year | 1997 |
| Genre | Beat-'Em-Up |
| Players | 4 |
| Status | imperfect |
| DLs | 102 |
Otenami Haiken
Otenami Haiken Final (V2.07JC 2005/04/20 15:36)
| Name | otenamhf |
| Mfr | Success / Warashi |
| Year | 2005 |
| Genre | Mini-Games |
| Players | 2 |
| Status | imperfect |
| DLs | 52 |
Otenami Haiken (V2.04J 1999/02/01 18:00:00)
| Name | otenamih |
| Mfr | Success |
| Year | 1999 |
| Genre | Mini-Games |
| Players | 2 |
| Status | imperfect |
| DLs | 30 |
Othello
Kyuukyoku no Othello
Othello (version 3.0)
Othello Shiyouyo (J 980423 V1.002)
Othello Derby (Japan)
Super Othello
| Name | sothello |
| Mfr | Success / Fujiwara |
| Year | 1986 |
| Genre | Tabletop |
| Players | 2 |
| Status | good |
| DLs | 10 |
Out Run
Out Run (Mega-Tech, SMS based)
OutRunners (World)
OutRun 2 (Rev A) (GDX-0004A)
OutRun 2 Special Tours (Rev A) (GDX-0014A)
Out Run (sitdown/upright, Rev B)
Out Zone
FixEight (Europe)
| Name | fixeight |
| Mfr | Toaplan |
| Year | 1992 |
| Genre | Shoot-'Em-Up |
| Players | 3 |
| Status | good |
| DLs | 58 |
Out Zone
| Name | outzone |
| Mfr | Toaplan |
| Year | 1990 |
| Genre | Shoot-'Em-Up |
| Players | 2 |
| Status | good |
| DLs | 99 |
