[The Fifth Horseman]

To help with timeframes we're talking back in the days when the monitors were RGB (only three colours) and I was only around 4 so 1986ish.

For the sake of correct terminology, that was CGA. When you use the designation RGB, you imply 24-bit mode (aka "True Color").

Any ideas?

Yes: http://www.mobygames.com/game/moon-patrol/screenshots