At bottom, such definitional questions don't matter very much. What Yu is doing, simply enough, is using some SFnal tropes in support of purely mainstream aims. That does affect the audience, of course. The novel isn't really interested in the mechanics of time travel, nor in a fully plausible future. Nor should it be. It's interested in the main character, and in his mother, and in his time machine's operating system (look, SFnal tropes again!) who has the personality of a sweet woman he's never really noticed while mooning over the girl he never married. And most of all, it's interested in Charles Yu's relationship with his father, an immigrant to the US, who struggled for years in his garage to invent a time machine and make something of himself. And who disappeared after his invention failed and someone else beat him to it.

But all that said, the novel isn't just another boring mainstream book about a guy trying to understand his father¹. The SFnal furniture really does make things work. We know from the start that everything turns on a time loop engendered by Charles Yu killing his future self, and on the paradox that the book we are reading is a book he could only write by reading the book his dying future self gave him. Charles' mother is stuck in a time loop herself, reliving one of her few happy moments, or so Charles believes. And the entire "Minor Universe" in which the action takes place is a satirically altered version of our world -- or perhaps it is somehow our world? -- a minor universe slightly damaged in construction. The SFnal tropes, then, are not interesting as Science Fiction, per se. We don't care that this novel isn't in any serious way about the possibility of time travel. But the tropes work to help tell the story, and to make serious points about the central characters, and satirical points about the "real world." And that's as good a use as any.

I haven't said a whole lot about the plot of How to Live Safely in a Science Fictional Universe, and I don't think I have to. The book works not because of plot but because of voice, character, and a humorous but bittersweet attitude. It's not an earthshakingly brilliant book, but it's a very enjoyable first novel, from a writer with real chops.

¹ Let's take it as read, shall we, that there are plenty of wonderful, not boring, mainstream books about a guy trying to understand his father.