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.
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.
Eventually I found it had been working all along-but didn't show anything on screen until it had the first full page of text. I inserted 30 new lines, and suddenly my toy said 'hEllO woRlD'. An hour later I understood alphabet shifting rather better!
Writing a really general parser is a major but different undertaking, by far the hardest points being sensitivity to context and resolution of ambiguity.
A deliberate choice on my part was for the player to continue to find new possibilities in the early Attic rooms far into the game. I think this builds atmosphere, though it means there's no neat division of the prologue from the middle game.