The 'interactive fiction' format hasn't changed in any fundamental way since the early 1970s, in the same way that the format of the novel hasn't since 1700.

Then in my early teens, when the home computer bubble was blowing, I had one of the first, an Acorn Atom, and used to write primitive adventures on that.

Writing a really general parser is a major but different undertaking, by far the hardest points being sensitivity to context and resolution of ambiguity.

The most frequent complaint is that it's hard. True. it's a hard game to win Also, many people ask me how to use the secret debugging commands, apparently under the impression that I'll tell them.

Players very widely disagree with me about what's hard and what's easy. and in a way, 'I won, but it was a fight' is the best compliment a game can receive.

If you're setting a game during the Cuban Missile Crisis, look through a library. find out what people were wearing, what other issues were in the news, how houses were furnished, what cars were being driven. Especially include things which now seem foreign.

I try to make puzzles range all the way from easy to hard, and to leave many open at once.