O

Overkill HD installer by Ralf Huvendiek.
Odyssey (Audiogenic) HD Installer & fix by JF Fabre. info here
Operation Stealth (Delphine) HD Install & fix by JF Fabre. info here
Oscar AGA (Flair) HD Installer by Thomas Kessler. info here
Oscar CD32 (Flair) HD Installer by JF Fabre. info here
Overdrive (Team 17) HD Installer by JF Fabre. info here
OverKill HD installer by Ralf Huvendiek. info here
One Step Beyond HD installer by Keith Krellwitz. info here
Operation Firestorm HD installer by Keith Krellwitz. info here
Operation Wolf HD installer by Keith Krellwitz. info here
Ork HD installer by Keith Krellwitz. info here
Out To Lunch AGA HD installer by Keith Krellwitz. info here