Ojousan (Japan 871204) MAME 2003 Plus ROM ISO

Oriental Legend Special – Xi You Shi E Zhuan Super (ver. 103, China, Tencent) (unprotected) MAME 2003 Plus ROM ISO

Omega MAME 2003 Plus ROM ISO

Omega Fighter Special MAME 2003 Plus ROM ISO

Omega Race MAME 2003 Plus ROM ISO

2 On 2 Open Ice Challenge (rev 1.21) MAME 2003 Plus ROM ISO

Operation Wolf (US) MAME 2003 Plus ROM ISO

Operation Wolf 3 (US) MAME 2003 Plus ROM ISO

Orange Club – Maruhi Kagai Jugyou (Japan 880213) MAME 2003 Plus ROM ISO

Orbit MAME 2003 Plus ROM ISO

Ordyne (Japan) MAME 2003 Plus ROM ISO

Oriental Legend – Xi Yo Gi Shi Re Zuang (ver. 126) MAME 2003 Plus ROM ISO