I'd have to add Ursula K LeGuin to the list of master's of crafting a world. The Wizard of Earthsea books are the standard for me, equal to Tolkein, of creating a world that was capable of changing over time realistically (even with all the magic). Even the three books she wrote decades after the original trilogy move that world's story forward.

Around 1977 or so on a huge basement-sized mainframe with some computer science major buddies. A great way to waste time and build up some nerdly coolness points. "Beg your pardon, captain?" Shortly afterward some of the predecessors of Zork, Colossal Cave, was it? Later, Parsec on a TI 99/4a used up a lot of my time. The first few King's Quest games. Lot's of computer and console games since. I'm having to compete for time on Super Mario Galaxy now with my kid. My son's friends (or my wife, either) can't believe that I like to play games now so much, though the real pleasure still is in the puzzle solving.