I don't know for sure if we had that topic already but anyway, it's rather interesting. I found this JavaScript code on GitHub:
https://github.com/hunterloftis/playfuljs-demos/blob/gh-pages/terrain/index.htmlOnly 130 lines of code for a nice result. Maybe someone port this to his favourite BASIC ...
I thought about that topic because they will release
No Man's Sky soon. Really impressive what they've done. Almost everything (even the soundtrack) is generated procedurally... and as a result there will be 18,446,744,073,709,551,616 planets to explore. AFAIK the game consists "only" of 600,000 lines of code.