OAKLEAF

Shuttle Pilot

OCEAN

Daley Thompson's Super-Test Hunchback-elk Mr Wimpy 
Match Day 
Daley Thompson's Super-Test-disk 

OIC

Dodgy Dealer

OMEN

Land of Tezrel

OPTIMA

Asteroid Miner Atomic Protector Bed Bugs Sea Wolf

OPTYX

Bomber Baron

OPUS

A Maze In Space Dogfight Dogfight-elk