I love a fascinating little mystery, and this one played out beautifully. Our hero has been in a self-destructive, alcoholic funk for a while, and then his ex-girlfriend gives him something that, she says, she'd ordered back before the split. It's an old typewriter with a bundle of old correspondence. It appears that Mr Astor, the previous owner of the typewriter, died under mysterious circumstances, and the correspondence holds the key to the mystery. Only it's all very cryptic: each time you pick up a letter, there are three possible follow-up letters attached, and you have to pick the right follow-up based on clues hidden in the body of the first.
It's not exactly realistic as a form of communication. My guess is that the original correspondents did not actually write up three different responses and expect the addressee to pick the right one, in the manner that our hero is doing. Rather, I would guess that there was always only one follow-up letter, containing the answer to the riddle of the previous; but, with the letters all jumbled up, our hero must put them back in order, using the knowledge that a letter with a riddle must be followed immediately by the one with an answer. But it's very convenient that the correct follow-up is always one of the three that our hero picks up after a a riddle. More realistic, and perhaps a more interesting puzzle, would be to have all the letters available from the beginning and actually have him slowly sort them out.
Still, I enjoyed puzzling out the riddles as they were. I note that correctly solving a riddle allows you to read a third letter, one without an expected follow-up; so six riddles solved correctly means eighteen letters read -- unless I'm forgetting any exceptions -- which ought to give you some idea of what actually happened to Mr Astor.
Unfortunately, there's nothing to confirm your solution except the game narration itself. Unless our hero can hear the narration of his life, he isn't going to know that he'd guessed right. I don't know, this seems like a real point of annoyance for me. It might not matter in a game like Zork, where there's a definite GM/player dynamic, but this game is well-written enough that the narrator fades away, and our hero is not a player in a game but a real character in his own story.
Anyway, like any good mystery, there's also a more personal side plot, this one involving our hero's relationship with his ex-girlfriend. It seems to me that the player could easily ignore the letters and pursue this instead, but I suspect that getting anywhere here would also require solving a few of the mysterious letters.
All in all, I think this was a well-written piece that somehow managed to fit cryptological puzzles into a narrative structure. As a breakfast, it's a crepe folded over a helping of fruit (blackberries! lots of blackberries!) and English cream, with sweet lemony biscuits and jasmine tea.