ZK Spectrum you say? I got three words for you: Lords of Midnight.
Ring a bell? Yes? Now that was an amazing bit of programming. 4000 areas (With 3D terrain view in 8 directions from each one for 32000 (nearly) unique views), several factions, over a hundred recruitable NPC's with armies - including some monsters, like Farflame the Dragonlord and so on.... all in 48k!
That is the first truly epic game I played, and a huge inspiration later. (This was before Elite). Doomdark's revenge was several times larger.... and still just 48k (!). Think about that... 32000 views, in a machine where you can only store 48000 Bytes. (A byte is enough to store one ascii letter, or a number up to 255.
Remakes are still being made... one of the better seems to be this one: http://www.frozenempire.net/remakes/lom/lom.htm
It was made by Mike Singleton, who is currently a 'bug hitman' over at Codemasters, I've been led to believe.
But yeah, I'm a youngster, almot, by these standards. (Just 39.).
There was a game... I don't remember its name, but it was a star trek game, in basic, on the C64. That was my first modding project.... good times. 