Damocles.
(see: http://en.wikipedia.org/wiki/Damocles_(computer_game) )
Basically, this game is like
Elite only you can
land on the planets
and walk or drive vehicles around the cities like
GTA, enter buildings, etc.
It came out in 1985.
I've never played it, yet have been working on my own game since 1988 with the aspiration of someday doing something with its
scope.
Before you ask, I have spent those 20 years researching/designing/building the tools I think I will need to do such a large game unaided.
Good thing it is only a hobby...